Jeff Perrin

Nov 182016

About a year ago I got the bug to do something really different for the new 2015+ WRX. With the FRS/BRZ being well established in the aftermarket world, some really well thought out supercharger kits had started emerging. This got me thinking about adding a supercharger on my WRX! Its the same motor right? It should just bolt right on right? I contacted two companies to see about getting a supercharger to test fit to really see what is involved. There were two really high quality kits that I thought would be perfect for my project. Cosworth’s kit was kind of the primo kit out there, it was the most expensive and had really good charge coolers mounted inside the intake manifold. The problem is cost. Cosworth/RallySport Direct (Cosworth USA) wasn’t able to give us much of a discount as their kit was new, in super high demand and not available for a month or more. They were a little leary as the project wouldn’t have benefited them in selling more kits. We were in the same boat as this was going to cost us a lot of money and a lot of time/money and it may be for nothing. Then I found the Harrop TVS1320 kit one day. I fell in love as it just looks sexy under the hood on the BRZ. At the time Harrop was interested to help us out with the project but there was a huge delay on when we could get one. While both Cosworth and Harrop were willing to help, the delay in getting kits really killed the momentum with this crazy project.


Fast forward to this year (2016) and the bug bit me in the ass again. There were plenty of people with bigger turbos and lots of power, but still nothing as unique as a twincharged WRX. I hit up the same two companies to see about helping with the project. This time around Cosworth/RallySport Direct had taken this idea and started down the path of installing it on their SEMA WRX. I thought great, we can do this together… except that once again, the kit was out of stock for a couple of  months. Harrop came to the rescue and was able to ship us a kit within a few days! Perfect and not to knock the Cosworth kit or RSD for not having one, but the Harrop kit was actually my first choice because it looks sooooo good. My only hold ups with their kit was the fact that I had never seen one in person, and the fact very few BRZ guys had them. What makes up for that is their willingness to help us out, their killer water to air intercooler system, and completeness of their kit.


Why even do this? The one thing I have come to love about modding cars is the response you gain from the turbo/engine. Anytime you do something you gain some response or something that makes the car better. This is great for a while until you get used to it and you want more. Well I wanted more! Adding the instant response (boost response) of the SC, along with the midrange power of the turbo, this would make for a killer setup as long as it all worked. Secondly the stock WRX turbo doesn’t hold boost past 5000 RPM and having the SC and turbo working together, this should allow for higher boost at redline. In theory, this had the potential to do great things if it all worked. And if it didn’t work, at least it would look really awesome!

With parts on the way, my excitement grew and was compiling a few things needed to make it work. Since RSD had already been installing the Cosworth kit on their WRX, they gave a few things to have to look out for. In return we offered to help them with the front mounted intercooler needed, the tuning aspect and overall setup. I still had reservations with a few things like fitment, tuning, and would this all be worth some kind of gains we couldn’t get from a turbo. I was confident enough that I didn’t care, and I would make it work one way or another.


What was needed to make it fit? Lots of grinding, and also lots of grinding. I would have made really tall spacers to clear a few of the obstacles, but the kit nearly fits perfect without that. I ended up making spacers that reduce some of the grinding, and added space for the bypass valve, but mainly they were made to create the transition from the BRZ sized ports to the WRX heads. You would think that these engines are exactly the same, but their heads have different port sizes and bolt patterns.


I started out building it in stages working up to the final install. Like installing the WTA (Water to Air) intercooler plumbing and pump. It fit amazingly well behind the PERRIN FMIC and bump beam. Even the custom molded hoses that Harrop includes for the BRZ work pretty well. The pump and harness they include worked very well. As you can see the pump mounted perfectly behind the intercooler pipe, I just had to extend the wires to it.


Once that was all done, the next hurdle was the grinding aspect. The AC bracket required a lot of material to be removed. This was to clear the throttle body and also to make room for the dual port bypass valve. It took about 4 times to get it right and also make it look nice. The throttle body needed some massaging too. Grinding all this down with a proper die grind bit is easy compared to what was next. The clutch slave cylinder was about 3/8″ in the way. The easiest way to remove all the material was to do this on the car, but imagine removing a 1″ x 1″ x 3/8″ block of steel with a die grind tool. Not only is it time consuming, it is soooo messy.

The rest of the install nuts and bolts things. Playing with belts and pulleys to get the best wrap and belt tension was the big hurdle.  As you can see it looks very OEM like.


I was able to utilized 95% of our 15+ WRX FMIC kit to make this all work. That was important as there could be a day that enough people start do this and I didn’t want to create something that is over the top custom. The one custom part of the intercooler was the last charge pipe before the supercharger. With that said, it is setup so that the WRX turbo system is all in place just like it was, but it is feeding boost to the supercharger. The heated and compressed air from the turbo is being cooled by our front mounted intercooler, then compressed again from the supercharger, and cooled one more time by the built in water to air intercooler within the intake manifold. You could call this twincharged and twin intercooled!

The moment I took off for the maiden voyage, it was very obvious (even with the lowest boost pulley) that this would need some taming of the throttle as the SC adds a huge amount of response! I drove on the car with the 95mm pulley at first to understand how this whole system would work. Being that this pulley should create a boost curve of 4.5psi at 2500 ramping up to 7.5psi at 7000, I was hoping to see boost to run about 15psi ramping to 18psi at redline. I was WAYYYY  off!

There are a few factors to why I was wrong. One being that the supercharger is compressing air at a ratio (pressure ratio). The supercharger is taking ambient air pressure and compressing it at a ratio to make boost. Compressing the boost from the turbo at this same ratio ends up multiplying the actual boost pressure instead of adding it up. This means, it should be running more than (turbo boost plus SC boost). The thing is this still didn’t really show what I was seeing, especially at lower RPM.

The other factor (the bigger one) is even with the turbo running off the wastegate pressure only (10-ish PSI), the added energy from the superchargers boost spools the turbo even faster. This created a rising boost curve out of the turbo (18psi verus 10psi), which added to the natural rising boost curve of the SC. I would see 25psi at 4500, and it was still going up! Obviously this is a bit much for pump gas and stock motor. My goal was to be able to a minimum boost level that would  allow the stock ECU safety parameters to function. That way if the ECU sees too much knock or has a legit CEL, it would drop boost to a safe level. So obviously this crazy boost was not ok.

Fast forward to today and after about 4 or 5 versions of control systems, I finally got it dialed.  It is so good that I took it one step further and installed a 10mm smaller pulley to make even more boost down low.  This would not  have been possible without the dual port bypass valve Harrop includes and our EBCS Pro to control it. I can run at little as about 12psi or as much as probably 35psi, all fully controlled by the ECU.




As you can see by the pictures, I have a water meth injection system installed into each runner. I ended up doing this as injecting the mixture into the SC inlet would destroy the coating on the compressor. I have been using the Aquamist HFS-4 for a long time now, and it was a must to integrate this into a high power WRX that can’t run on E85 or run high quality fuel. With the carbon build up issues, blow by from the crappy PCV valve, EGR stuff, and also being able to make power on pump fuel, every 2015+ WRX customer should consider running a water/meth injection kit.


Why did it take so long to show this off? Its actually been running on the car for the last two weeks but there were many things that had to be worked out. Mainly was boost control but other things like oil cooler setup, routing of things, visual appearance, and most important was tuning/drive-ability. I didn’t want to show it off in its testing state with hoses and wires everywhere. Nor did I want to fail at answering peoples questions that I am sure would be asked.  As of two days ago all of this came together to a point where I was willing to show it off, and it turned out WAY better than I expected!


Does it work and was it worth all the effort are two really important questions. Absolutely! The response is amazing at all RPM’s, and the best part is there is virtually no turbo lag. If you are cruising at any RPM there is an instant 6psi of boost on tap. The higher the RPM the most instant boost you have. Even at 2300 RPM, if you go from 0% throttle to 100% throttle, it instantly hits 6.5PSI, and in .6seconds, I am seeing 17psi. At 3500 its even better. And it is even MORE responsive if you are at part throttle then smash the gas (because the boost tubes have some boost in them). So yes… it works and yes, this whole thing was worth

There is only one question that I can’t answer at this time, which is “How much power does this make?”. Dyno time will follow very soon. Every day, I am tweaking the setup dialing it in, working out bugs in order to get it on the dyno. I can say for sure that it absolutely makes power, and it a blast to drive! I will post up some good data with boost curves and things showing where the SC blows the turbo out of the water in the next few days.






 Posted by on November 18, 2016 Project Builds Tagged with: , , ,
Nov 192015


One day I was doing some R&D work on our WRX and noticed how sloppy the steering felt when the car was in the air. For whatever reason I was turning the steering wheel back and forth quickly and I could feel a strange rubbery feeling to it. This rubbery feeling drove me to look at the steering rack closer as well as all the mechanisms in the car. What I found was the steering dampener on the rod going from the firewall to steering rack. With the help of an employee doing the steering while I was under the car you could see this dampener squishing a bit and the wheel would go from left to right. After further testing, we found there was quite a bit of deflection when the wheels are locked down. Check out the image below and you can see how bad the steering rack universal joint dampener flexes!


It is pretty obvious that this is moving and deflecting but how does this translate to the driver while on the road? Imagine you turn the steering wheel and the wheels don’t actually turn. That is essentially what is happening here, but not quite as scary as that may have sounded. This dampener is in place to reduced feedback from things like ruts, bumps and vibrations that may translate form the road.

I had never noticed this part on my other cars partly because they were mostly STI’s. These cars do not have a dampener installed on the steering rack universal joint, they are just a straight rod. Obviously Subaru did this to give the driver better feedback, and make the car handle a little better. For this customer base, they wouldn’t mind that additional feel from the road, where WRX (and most all the other Subaru’s) are being sold to customers that are looking for something a little more subdued. The question becomes, does removing the dampener negatively effect anything? We will get to that in  a bit.


Solution, OEM STI Universal Joint?

Why not just install the OEM STI part? First off, it costs more than $150, which is almost twice the price of the part we sell. Secondly the installation for this is not easy. You need to drop the steering rack, and make sure the steering wheel and rack stay aligned during installation. My guess is a shop would charge roughly 3 hours labor to install the OEM STI part. Our part installs in about 10 minutes on the 2015’s! Other cars take anywhere from 30-60 minutes depending on if you do it from the top (removing the intercooler) or from underneath the car. Between the price of the parts and installation, our part could save you almost $300!


How Does Our Part Feel Once Installed?

Things like ruts in the road, bumps, and other things are transmitted to the steering wheel, are numbed by the OEM dampener. Without the PERRIN Steering Dampener Lockdown in place, as you turn the steering wheel there is a delay when the actual wheels turn. Also just the opposite, as  things push on your wheels trying to turn them, the dampener has to flex before transmitting that to the steering wheel. That means your car can steer it self in a direction you don’t want, while the dampener flexes.

Once Installed, the best way to describe it is there is more “feel” to the car. You will notice in situations like the middle of a corner, you might normally make tiny corrections to keep things pointed the right direction, or you don’t correct your steering and the car moves around a bit. With our steering rack lockdown installed, your car just goes where you tell it to. You may even notice how you are automatically correcting the wheel with ruts in the road as you can now feel them and let the steering wheel do it’s thing as you drive over them. It is hard feeling to describe but once you install them, you will quickly find out how much better the car feels. Personally, I don’t think any customer is going to complain about the added feeling.

 How Does Our Part Work?

Instead of making a whole new joint, we created this part that simply locks out the rubber portions of the dampener. This does the same job as replacing the dampener with an STI part, but without all the labor and costs! You can see the before and after in the moving GIF above how it completely removes the flex from the dampener. Without even saying anymore, that picture should sell you on why you need this part! The picture below shows you how both halves comes together during the installation. This not only pulls the rubber pieces together, but also stops the upper portion from rocking back and forth. You can see this motion in the above moving picture.



What Cars Will This Fit?

After designing the part for the 2015 WRX, it was important to work backward with what else it will fit. Essentially every single Subaru model other than STI, has a dampener withing the steering rack universal joint. What we have found is that around 2005-ish, Subaru changed the part in a way that allows our part to fit. Using the picture below, you can see a gap through the side of it. The distance from the bottom of the archway, to the top of the flat surface must match this.


We created this diagram to help determine if it will work on their car, which helps us narrow down the specific models and years to exclude. Currently it’s the 2004-2006 cars that seem to randomly have different dampeners installed. Check out our website for the most up to date list. It is a giant list that grows every day! We would love to hear from everyone that installed this on cars other than the cars we have listed, so please feel free to email us and let us know!

 Email Us!

Nov 032015

The Idea

A while ago, a customer said something to me that made me think about a better purpose for the PERRIN Horn Bracket. I mean everyone loves a good horn and loves that look of the Hella horns behind their bumper. But really, who uses their horn enough to warrant that. For a matter of fact, why not just install some red circles behind your grill :)

Ok, kidding aside, while horns are good to have and I loved my Hella horns on my 2015 STI and other 2015 WRX, I wanted to install something that was functional but still looked cool. Why not some LED driving or fog lights?  They would show up while turned off, they would actually allow you to see better, and it would be something I would use everyday (especially in the winter).


I started with researching LED lights that were smaller than 5″ and reasonably thin. There were so many to choose from and after getting a few samples of some high end lights, i found most to be really heavy because how how beefy they are made. Even though our Hella Horn Bracket is really thick 304SS, I didn’t want there to be small vibrations that would cause the lights to jiggle while driving down the road. After doing some digging, PIAA has a bunch of lights that would work. Since they are local to us and we have a nice hook-up there, I was able to test out a few.


I settled on some PIAA LP530’s, but a close second was the RF 3″ cube lights. Both fit perfect, look great, and are pretty lightweight. This is important as many others were about twice the weight and could compromise our bracket over the life of the car.


Everything you need comes with the PIAA lights, and the only thing I did is use my own M8 hardware to mount them to our bracket. Even with the bumper removal, the whole install only took about 1 hour. This was done on my Base WRX, and since it didn’t come with fog lights to start with, I had to install a switch. Had this been on a car with fog lights already installed, this would have been even easier!


What Car Will This Work On?

This works on the 2015+ car because the distance between the bracket and the gill is huge! I would say almost any light that mounts on center with the light will work on these cars (as long as you consider the weight). The 08-14 WRX/STI also has quite a bit of room but its the other cars that won’t work. There just isn’t enough room on the 02-05 cars and the 06-07 cars the grill will cover up too much of the light.


If you are not using a PIAA light, consider the lower profile the light is, the better chance it will fit behind the grill. The lighter they are the better to reduce the amount of bouncing around that could occur. The bracket for the light must be able to mount behind and centered with them as well. Lastly consider the outside diameter of the light and stick with something smaller than 5″.

This whole idea only works, because our bracket is made from heavy gauge stainless steel. Other thinner brackets, ones with a million holes,or ones from aluminum are not going to hold up, and or will cause the lights to bounce around a bunch. We over built ours to be able to handle the heavy Hella horns and it just so happens to work for LED lights!





Lights on…


Lights off…


The idea of installing some LED lights on a PERRIN Hella Horn Bracket is 100% valid, and 100% something we expect people to start doing! Trend started here! At least, I think it was…

It happened to be a nice foggy day during the pictures. It does make them a little grainy, but you get the idea.




Oct 302015

See our Poll on NASIOC to help us figure out which style you like!    NASIOC Poll for PERRIN Gurney Flap


How This Came To Life

Like a lot of parts I come up, it starts with something I make just for my car that I think no one else will want, and then it turns into a real part. This is exactly how the Wing Riser Kit for the 08-14 STI Hatchback happened as well. One day I made a bunch of spacers and pieces to raise the wing off the car and next thing i know, people wanted it!

In the case of the PERRIN Gurney Flap, it happened exactly the same way. Adam bought one of the Camaro Z28’s with the Wicker Bill option and it got me thinking about doing that on my car. Just like the factory GM part, it would require drilling, and I was willing to do it as worst case I would just remove my wing. After finding center of the wing I went to town and drilled some holes. At this point the guys in the shop thought I was crazy drilling holes in my new car… I installed the inserts, cut some cardboard then started shaving into shape.


This part is a hard one to figure out because it can be made so many ways. Taller shorter, longer sharper, rounder and different materials. Literally, there are endless options. After lots of opinions and 4-5 versions of cardboard, I made a metal one and drove around for a few days deciding if it was cool or not. So many people actually liked it, that it started to become a potential real product for us to sell. The next step was to have a couple versions laser cut and install them on the car to get customers opinions. As of this moment the project on hold while we seek help from the Subaru Community. What style do you like? What do you NOT like about it? Any reasonable suggestions will be taken into consideration. We would love it if you participate in our polls we have going on social media, your opinion matters!


Product Details

What does this fit? Specifically, this fits any 2015+ WRX with the low profile trunk spoiler option. This comes standard on the Limited and Premium WRX, but it is an optional part on the WRX Base and STI Limited. We have seen the low profile spoiler installed on some of the Impreza Sedans, so there could be a few other models this fits. For now we are focusing on the WRX and STI models.

How does it install? We are currently tweaking the instructions, but quick version is this: Locate your first hole (center of wing), drill and install supplied insert. Bolt on Gurney flap, and use part to locate remaining holes (making sure they are centered vertically on spoiler). Double check measurements then drill remaining holes and install inserts using supplied tool. Bolt on wing and done! Beside being timid to drill some holes in your car, the install should be 1 hour or less.


How does it function? We have not tested this in our wind tunnel yet (we don’t’ have one actually) nor have we done any CFD testing.  Most likely will not go to those lengths until we get a little deeper into the project. At this point the primary function is looks as it adds a nice clean edgy look to the WRX’s and STI’s with the low spoiler installed. For sure this part does add downforce, but the amount it adds isn’t something we are going to provide to customers right away. Until then think of this part as a dress-up/rear deck lid cleaner. You can totally tell that it is working since the top of the trunk lid stays very clean.

Here are a few more pics to help.

gurneyrear2      gurneyrear1

Gurneyside1      Gurneyside2

Gurneyside3        Gurneyside4

gurneyfinal1      gurneyfinal2      gurneyfinal3

 visibility1       visibility2       visibility3

As this project progresses we will post up more info!

Email Me with any comments!

 Posted by on October 30, 2015 Part Design & Tech, Project Builds Tagged with: , , , ,
Oct 282015

Upon the release of our PERRIN Electronic Servo Driven Gauges, we stumbled onto a perfect part to make, that would compliment them being installed on a 2015 WRX or STI. Something everyone would need and could afford!

In the past, we would have to slit a large rubber boot behind the turbo to fish wires and things through to get from the inside of the car to the engine bay. This was a simple location, but the issue is water and noise. Doing this opened up the door for water getting into the passenger foot well as well as you would hear engine noise a bit more. We just dealt with this on the 2002-20014 cars(as I am sure everyone has), but now on the 2015’s we stumbled across a pretty cool solution.


Subaru was nice enough to install a hole in the firewall just for us to use for passing wires and other things from the interior of the car to the engine bay. I know, they didn’t do this just for us, but we saw a perfect opportunity to make a part that any customer buying gauges, or installing things like water methanol injection or NOS systems would use. You can see the location of the hole in the above picture, which is in the same place on the STI and WRX. There difference is on the WRX, there is a simple plug where the STI has the sound generator tube installed. This is that weird tube that connects to the intake system and pipes sound to the inside of the car.



This hole opens up to the cavity where the windshield wiper motor/hardware resides as well as where the HVAC system sucks in fresh air. Within this cavity is another hole that is perfectly located to run wires and/or hoses completly out of the way of a passenger (or driver if in another country) and down to the frame rail. Just like the engine bay hole, it is covered by a plug on the WRX and on the STI the remaining section of the sound generator passes through it. In both situations, running regular wires through them will leave open holes, let in sound, water, air and look terrible, so we designed the PERRIN Firewall Grommet!

asm-gau-120_01 asm-gau-120_04

The PERRIN Grommet was the first rubber OEM type part we ever made. We have made many previous parts in urethane, but in testing, we just weren’t happy with the way it looked or functioned.  Using OEM type molding methods, we were able to create a part that will perfectly compliment any engine bay. You can see in the pictures below an example of  our plug being used during an installation of PERRIN oil pressure, fuel pressure gauges, and an Aquamist HFS-4 system. There is plenty enough room for 8 separate wires and hoses passing through it. In this example there is enough room to run 4 more sets of wires for gauges and maybe enough a power wire for a stereo system!


You can see in the bigger picture that all that is left to do is snug up the zip-tie and the installation is complete. We felt this was and important feature to ensure the wires were secure as well as relatively sealed from weather and heat from the engine. The


One last thing! If you look at the WRX and STI pictures you will notice that there are two holes! That means there are two places to install a PERRIN Firewall Grommet. While we will be selling them separately, we do expect most customers to buy two at a time. It is such an inexpensive part that there is no reason to not get two :)

We expect this part to do well enough that we will expand this into other sizes and fitments for other popular Subarus. So keep an eye out for more items like this from us!

Sep 222014

If you read the entire post from 2015 WRX and STI Exposed article, you would know that the 2015 WRX shifter is one of the things that I feel is terrible about the car. Normally cars that use cable shifters have a very positive feel and provide excellent feedback, but that is not the case for the 2015 WRX.

This all started the first day I drove the car for an extended period of time. I first hated how the shifter felt regarding the distance between gates. It felt like 1/2 gate was really far away from 3/4 gate. Then 5/6 gate was really close to 3/4 gate. This led me to dig into the shifter more and figure out why this is happening. What I discovered was that the shifter is really sloppy feeling when its in gears 1 and 2 and really tight in the 3rd, 4th, 5th and 6th. This gives you the false feeling of the gates being weird. So how can we fix this slop? Easy……


The PERRIN Shifter Stop is the first of its kind for PERRIN as well as any Subaru. This wasn’t something we ever NEEDED to design before since the transmissions generally shifted really well. If you are a past Suby owner, you a probably wondering how sloppy the WRX shifter is, if you are going to notice this, and then how does this thing work. All good questions, and to be answered below.


How Sloppy Is The WRX Shifter?

Using the diagram below, you can see that there is a huge amount of slop in the 1st/2nd gate compared to the others. These measurements are taken in gear at the end of the knob and with very light action moving it left to right. You can add about .25″ to the below numbers if you push on it left to right with a bit more force.  The 1st/2nd gate is so sloppy that it almost feels like its in neutral on a normal car, so when this slop is removed, its amazingly different.  Almost to the point of making the car shift as good as the 6spd STI tranny.


After installing the PERRIN Shifter Stop, you can see how much this tightens up the slop. Going from 1.00″ of loose sloppy feeling in 1st and 2nd, to .12″ is very noticeable. Even people that have never driven the WRX notice how much better this feels just sitting in the car.


How Does This Part Work?

As you can see from the above diagram, there is a varying amount of slop in each gate. The PERRIN Shifter Stop only fixes the slop found in 1st/2nd gate. 3rd/4th gate is already very good because the internal parts of the transmission have very little slop in them. The 5th/6th gate changes because we have you adjust the OEM shifter stop to help tighten things up a little. The OEM shifter stop is mainly used for locking out reverse, but doubles as a shifter stop, lucky for us that it is adjustable!


You can see the OEM shifter mechanism above and how the PERRIN Shift Stop is similar to the OEM part but for the other side. When you place the transmission into 1st or 2nd gear, the shifter has nothing for it to rest against, so the play that exists inside the transmission (shift forks, syncros and rods) all gets translated to the shifter. In this case it’s more than 1″ of free play!

The PERRIN Shift Stop creates a physical stop on the shifter to shift rod mechanism, this controls the amount of slop translated from the tranny to the shifter. When properly adjusted, the amount of free play goes from 1.00″ to about .10″. Not to mention, the feeling of putting the transmission into 1st, or downshifting into 2nd is significantly improved and feels much more solid.


Besides removing the slop found in 1st and 2nd, you will find going from 2nd to 3rd and 5th to 4th is much more natural feeling and much more positive as the slop doesn’t translate into the sort of lost feeling of which gear you are in. One complaint I had before was the distance from gate to gate being different, and that completely goes away after installing the PERRIN Shift Stop.

This part is like many of our other shifter bushings an short shifters, once it’s installed you will wonder why Subaru didn’t just make it like this to start with.


Bonus Fix Included

Another thing I found while coming up with this part is the whole shifter mechanism moves around a bunch as well. The biggest culprit of this is the gap you can see in the below picture. Like with everything, there is a tolerance in what something is made to. In this case, the tolerance between the shifter mechanism parts is pretty large. You would think that the OEM bolts would suck this close, but they do not because they are a shoulder bolt. When they are tightened down they do not actually suck things together. We include some special SS washers that allow this gap to be closed up when the nuts are tightened. This tiny amount of flex translates into a much larger amount of flex the top of shift knob.



One of my favorite things about modifying cars is improving the way they feel and this part is a perfect example that. It makes such a huge improvement and is so noticeable, that it will bring new joy to your driving experience. This will be a mod that everyone will want and everyone can afford. Add the also affordable PERRIN shifter bushing to this same installation and you will be very pleased with the way your 2015 WRX shifts. This doesn’t only apply to 2015 WRX customers, but also 2010-14 Legacy/Outback with manual tranny, and 2014+Forester with  Manual tranny.




Jun 202014

We can make this really simple. If you live on the east coast and/or  own a 2008+Impreza/WRX/STI/Legacy and have more than 40,000 miles on your car, you need this part. Click HERE!

OEM Bushings Will Fail…

Ok being serious now, there are many reasons to want this part. They fail, they are super soft, negatively effect handling under braking and acceleration, and can add to wandering of your car from ruts in the road. Secondary reason to want this part is the added caster and removal of anti-dive/lift geometry to the front suspension, which helps with weight transfer under acceleration and braking. The most common reason to buy them is they fail. As you can see the picture below from a Legacy GT (Shares the same control arm as the 08-14 WRX and 08-10 STI) where the bushing ripped at 34,000 miles. This is more common to happen at 60K+ but still its not good. When the bushing rips, the control arm becomes loose vertically in the car, which then leads to a loose feeling in the front end, shakes in the steering wheel, and clunks as you go over bumps. In extreme situations (like hard driving or track day) the arm will slightly dislodge its self upward causing a constant misalignment of the front end. This is really bad!

The cars that don’t need this for durability reasons are 2011+ STI and 2015+ WRX/STI. These cars come standard with a spherical bushing encapsulated in rubber (shown below). Since they are constructed much better, they don’t have that constant wearing and tearing happening at the rubber portion of the bushing. These cars still benefit from removing a flexible rubber bushing as well as the anti-dive/lift reduction feature.



Why Is This Called PSRS?

Something that annoys me is that we see people call these the PERRIN ALK or Anti-Lift-Kit. This is frustrating for few reasons, ALK is a term that another company came up with to describe what they felt was the main feature of their version of this part. Secondly, calling them an ALK or Anti-Lift kit, causes tons of confusion with customers as they think this parts reduces the amount of lift under acceleration they have. This is why we call our version of the LCA (lower control arm) rear bushing replacement as a PSRS (Positive Steering Response System). We feel that the change to the steering and feedback you get from the car far out weighs the features of the change to the Anti-Lift geometry. While both do good things is the other features that are more important.

The biggest benefit of the PERRIN PSRS (for all cars) is the removal of the squishy rubber bushing on the car. All of our kits replace the front lower control arm, rear bushing, with a bearing or a super hard polyurethane bushing to remove nearly all deflection under extreme conditions. Using the above picture, you can see how under braking, that the control arm will want to deflect toward the inside of the car, and then under acceleration, the deflection happens the other way toward the outside of the car. When the control arm is deflected either direction, the alignment of the front suspension changes. As an example, your car is setup with zero degrees of toe in the front, and under braking you will get toe in, and under acceleration, you will get toe out. This can cause the car to have bump steer, effects how the car handles and can change the predictability of the car. Removing this unwanted deflection will greatly improve how the car handles under extreme conditions and create a more positive feel between you and the road. Customers love how the car feels like it wants to go where you point it, versus wondering around or wiggling under braking.


This leads us to the next thing customers really notice, which is how your car will not want to follow ruts in the road. With a stock car with stock wheels and tires, you won’t notice this too much. The moment you put on stiffer suspension, and or wider wheels and tires, you will find that your car will want to wander in the road between the ruts. This happens for a few reasons, but one of which is the front lower control arm  bushings deflecting. Installing our PSRS significantly reduces this from happening and makes the car track much straighter on freeways and other roads that get rutted from heavy traffic.


The next biggest features is in our offset version of the part. Most of the kits we make are offered with an optional offset bushing/bearing. This adds .5-1.5 degrees more caster to the cars front suspension. Caster is the angle that the front hubs turn at. If you stand next to your car and look at the front wheels, you might think that when you turn the steering wheel, the wheels rotated perpendicular to the ground, but in fact they don’t. They always rotate on an axis that is offset toward the rear of the car (from the top of the hub). This angle helps do a lot of good things.



Why do you want castor? Castor helps reduce the amount of static camber needed on the front suspension. This helps with overall tire wear in a huge way. Imagine that castor increases negative camber to the outside wheel, and increases positive camber to the inside wheel making the angle of the contact patch of the tire better aligned to the road. Castor also helps the cars steering self center after a corner as well as track straighter down the road.

Most OEM suspension setups are done with a lot of compromises for alignment specs. Subaru has always been on the low side for castor specs, relative to other cars but that has changed over the years. For instance the 2002-2005 WRX has 3.0 degrees, 2004-2007 STI has 4.8 degrees, 2008-2014 has 6.25 degrees, and the 2015 STI has 8 degrees. You can see that Subaru has slowly changed it spec for castor over the years, and ending with what most people call the best handling Subaru to date.

Because of how we are adding castor, we are limited by the OEM control arm design  and how much we can add. In most all kits we are able to add .5-.7 degrees of positive castor and on a few we are able to 1.1-1.2 degrees. There are other ways to change castor, but not using the same front lower control arm bushing we are replacing with the PSRS.


So why doesn’t everyone get the offset bushing version of the PSRS? The only issue comes up when customers have really wide wheels and tires. Since we push the front wheels forward to get the extra castor, it pushes the wheels and tires closer to the fender liner. This mainly occurs on the 2008+ cars where 275 wide tires are a common upgrade. If that is an issue for y0u, then simply purchase the normal (zero offest) PSRS and you will have no tire rubbing or clearance issues at all.

Anti-Lift Geometry Changes

I hate the term ALK or Anti-Lift Kit.  From the beginning we have battle with this because the other companies Anti-lift kit isn’t keeping the car from lifting under acceleration or decelerating.    Its really an Anti-Anti-Lift kit or pro-lift kit.  The company that originally came up with the name describes the name as a fix for anti-dive/lift geometry, which has confused tons of customers, and also some of our team as well  :)

OEM’s build “Anti-Lift” geometry into the front suspension help make the car appear more stable. What this does is reduce how much the front end will dive under braking, or raise under acceleration. To most normal customers, this is a good thing making the car appear to be more stable, but this does have some negative effects as it reduces weight transfer from front to back.


How does Anti-Lift geometry work? Imagine if your control arm is perfectly level to the ground at all times. When you hit the brakes, all that force is being pushed front to back on the arm and the only thing that compresses the suspension is the weight transferring and bumps. Now imagine the rear of the control arm being lower than the front. Under braking, that force is pushing the arm backwards and up, compressing the front suspension slightly along with the weight transfer and bumps. With the rear of the control arm lower than the front, the suspension compresses more, and more weight is to transfer to the front of the car.

Now look at it from the perspective of acceleration. With the rear bushing mounted lower than the front, as the wheels are pulling the car forward, it extends the front suspension down raising the front of the car. This transfers the weight to the rear of the car. Weight transfer is a good thing (to a point) to help put more weight on the tires that need the most traction. For instance under braking, additional weight helps front tires have more traction, and under acceleration, more weight transferring to the rear adds more traction to the rear tires.

Changing the geometry away from “Anti-Lift” toward “Pro-Lift” has many benefits, but this is not something customers will pick up on and notice. This is why we feel that this is a minor feature compared to the other things mentioned previously.  ….



What Makes the PERRIN PSRS Different?

All of our PSRS kits over the years have been designed to be as deflection free as possible.  Our first version of our 02-07 WRX PSRS used a spherical bearing, later moved to a hard plastic Delrin bushing, which significantly reduced our cost while still being deflection free. From that point on we always tried to incorporate the more expensive spherical bearings where we could. All newer Subaru’s use control arms that have a vertically mounted round type bushings, which allows us to use the more expensive spherical bearing and keep the costs down.

Even more recently switched to a super hard polyurethane for our super popular 02-07 WRX PSRS. This allowed further reduction in cost and virtually no change to performance. While polyurethane is cheaper it does have its place, even with expensive cars like GT-R’s.


There are a few applications where a spherical bearing could be used, but it adds huge amounts of complexity to the part or sacrifices some amount of durability. For instance on the Nissan GT-R, we used a hard polyurethane instead of the bearing because we needed to be able to adapt our part to the OEM control arm. Same goes for the MINI Coopers as they have a strange hex shape that we adapt to, and it was easier to make this out of polyurethane.



Besides our use of spherical bearings in many applications, we also exclusively use aluminum for each PSRS body. We see the use of steel sleeves that house urethane or other forms of steel used for the body. This sounds great but any customer of ours that lives in the eastern states where roads are salted and corrosion is very high, these never last. And even worse, are almost impossible to remove after a few years. Making the housings from aluminum not only allows for removal at some point, but also they are significantly lighter than steel versions. Some even use urethane in place of a body,which adds to amount of potential deflection. The less urethane you can use, the less deflection will occur. In the above GT-R and WRX PSRS, you can see how the thickness of urethane is pretty small, making the bushing stiffer overall.

We also try to make them as adjustable as possible. This ranges from offering another part number that has an offset bearing, or being able to press the body into a control arm at a different angle, or something like the GT-R PSRS that has a housing that can be bolted in a few different directions. When we first launched our PSRS’s we only offered the offset style. After we had a lot of feedback from customers wanting a part they could install and NOT be forced to get an alignment done, we offered the zero offset versions. From that day on, we have offered both styles or offered one part number that would cover both.


Will I Really Notice The PSRS After Installation?

In most cases you will find a huge difference in how the car feels. But, that depends on the state of the car, which model of PSRS, and what car you are installing it on. For instance an 02 WRX with 130K miles will have a much softer bushing compared to a 2007 STI with 30K miles (uses the part).  So an 2002 WRX customer is going to notice this way more than the 2007 STI customer purely based on wear and tear. Another example is an 2008 STI customer versus a 2014 STI customer.  Between these two years (eliminating wear and tear) the 2014 STI has the newer larger rubber/spherical bearing type, and the difference in stiffness isn’t as large. This is why on a 2014 STI we recommend the Offset PSRS, which will absolutely make a difference.  As you can see the effects of installing our PSRS will vary depending on the car it is being installed, but in most cases the difference is very noticeable and will quickly become one of those things you wish the manufacture did from the beginning.


May 282014

New Tests Added May 28th 2014

Customers constantly ask us “How loud is that exhaust?”. We have a really hard time answering this question because how does one describe a sound? How can you compare this to something else? Even doing a video has it’s limitations because of how and where a microphone was placed. We thought we could come up with a way that can accurately give a customer a comparison between different cars, different systems and how they sound.

Step one, buy a quality decibel meter. Step two, figure out a way we could consistently test any car at anytime. Step three, start testing!



This Is Just A Test!

Keep in mind, these tests are ONLY for comparison purposes to help provide an answer to the question “How loud is this?”. These tests are not saying any of these systems will pass any local law pertaining to a decibel limit for your car. If you are unsure of a system passing a local decibel limit law, please have a professional test out your exhaust to determine if its legal.



Where To Place Decibel Meter

What we decided on was a placing the decibel meter in specific locations for each car, then holding and revving the RPMs up to specific points and recording the decibel reading.  We originally had 10 ft from the back (setting on ground), 5ft from the right (setting on ground), 5ft from the front (setting on ground) and inside the car (windows up). We found quickly that the 5ft in front of the car was louder in most cases than the side due to the engine noise.  After 8 cars of testing we gave up and stopped using that as a measurement.



What RPMs To Test

Next thing to determine was what engine RPM to hold while recording. Idle is an obvious one to record, as well as other RPMs that you might be constantly at. We chose 2000RPM and 4000RPM. The last one is a little harder as we chose to do an idle to 6000-ish throttle blip. This one isn’t quite as consistent, but the correlation from exhaust to exhaust came out exactly how we wanted it. We know we could have gone crazy and done way more, on the road, on the dyno, but we wanted to keep this simple and something a customer could easily understand at a quick glance.



What To Test

We plan to test as many things as we can. We plan to test the 02-07 WRX (with the single sided exhaust system), 08-14 WRX (sedan and hatch exhaust systems), 2015 WRX (with equal length header and lower mounted turbo), and BRZ. From there we will obviously test stock cars without modifications as a base, then after that, we will test all our catbacks, midpipe options, downpipes, front pipes, headers and whatever else might affect the sound coming out of the exhaust. Even if its something we don’t make, we will test it, if its not too much trouble. We will make a blog post that covers all the cars, the test and constantly update it as we add a few new cars.



Below are the graphics we came up with to show off the different readings we found. This graphic along with a simple 4×3 chart will easily explain the sound changes from stock to parts being tested. As you can see from the below diagram, the decibel meter was placed in three main locations, Inside of car, outside and to the side 5ft, and behind the car 10ft.



Along with the above diagram we will be including a chart that explains all the reading and the results. Most tests will have both the stock decibel reading as well as the decibel reading from the part(s) we tested. That way, there is a quick way to reference the difference in sound levels. Using the info provided below, you should at least be able to get a rough idea how much louder an exhaust might be. Or if you have heard one of the below setups, you can get a rough idea how much louder or quieter another one might be.

The idea is to create a consistent way to test sound levels of cars. This isn’t to prove the system is legal in your state, but only to provide a rough idea how different setups compare to one another. I think with the graphic we have, the data we have, and the ability to test any car quickly, we will have a really clean way to show customers how systems compare to one another.

Below are the results from all of tests we have done. We will constantly be updating this post as new tests are done.


2013-14 BRZ/FR-S






2011-14 WRX/STI Sedan







2015 WRX









May 282014

One of the features I really like about the the 2015 WRX and STI is the LED Headlights standard on the STI,  WRX premium and limited models. The headlights are absolutely amazing at night and are far superior to the older HIDs that came on the STI’s. Subaru did such a good job on this car and its hard to find things that are flawed and or need improving. With that said, there is one thing I found. The fog lights are terrible, don’t really do anything and they look out of place on the front of the car as they don’t match the LED headlights!


The reason for me complaining about this is they are just Halogen bulbs, which color wise are yellow and do not match the super bright blue LED headlights. Subaru stepped up to the plate and put LED headlights in these 2015 models, but didn’t think to keep that high end theme going with the foglights. You don’t any new Audi running around with halogen fog lights do you??


Replacing Halogen bulbs with HID or LED bulbs isn’t exactly new, but PIAA has just come out with an LED replacement H16 bulb that brings a super high quality LED option to the market. As you can see its more than just a bulb, but an actual controller and harness adapter that is waterproof to ensure it lasts a very long time.


AS you can see, the color is almost the same as the OEM 2015 WRX and STI headlights, so from nothing more than a visual appearance, they do wonders for the car. The nasty looking yellow halogens that came on the car (first above picture) really ruins how the new 2015’s look while coming down the road at you. From a functionality stand point they are actually functional now! Before the yellow-ish lights barely lit up the road and the main LED headlights were way overpowering. With the PIAA LED bulbs installed, they actually light up the road and make driving on twisty roads at night, quite a lot of fun.


Each bulb them selves is an electronic circuit that consists of the drivers necessary to run the super powerful LED. The housing is made of high quality die cast aluminum, which not only makes it durable, but also help dissipate the heat generated from the circuitry.



As you can see from the picture, this is a pretty solid unit with not only an adapter harness, but also a special controller that drives the LED circuit. Of course they plug right into the OEM harness so there is ZERO cutting and splicing. Only thing tricky about the installation is the direction they get plugged in. The circuit that controls the bulb requires a specific positive an negative connection to power. Since normal halogen bulbs don’t care which pin gets the positive or negative wire, car manufactures don’t consistently put them on the same side of the bulb. So PIAA has a harness that plugs in both directions. It’s a simple part of the the installation as you simply plug in the bulb, and turn on the lights. If it lights up you are good, if not, just switch the direction of the plug.

Now all we need is to get the LED replacement for the high beam bulbs!




 Posted by on May 28, 2014 Misc. B.S., Part Design & Tech Tagged with: , , , ,
May 232014

We last left you with the dyno graphs from the stock 2015 STI and WRX. We showed how the 2015 STI spools slower than the 2008-2014 STI,yet still makes more power by about 20 Wheel HP. We were slightly concerned that Subaru may have really pushed the car with the newest ECU tune and there wouldn’t be much for us to gain from an ECU tune.

Cobb offered us an Accessport for the 2015 STI long before they were released to the public. We were lucky to have this offered to us as it gives us something to keep the hype going with PERRIN and the 2015 STI. It also helps us with R&D on new parts we will be offering, and of course its a great way for us to help Cobb with making sure there are no bugs with the software. Also, I felt pretty special getting serial number 2 (#1 went to Cobb) of the new part number AP3-SUB-004! So how did this tune?



Dyno Tuning Time

Lance from Cobb came over to give me a few pointers about some of the minor changes in the software and also hand delivered our V3 Accessport. Essentially all the same maps are available to tune on the 2015 STI, but there are a few that changed that simplify ignition timing as well as effect it in different ways. Its not really important for the normal customer, but essentially its all the same, except for that weird added lag and additional HP it starts with.

Staring out the day we did a bunch of baseline runs with out the Accessport installed. This is important as it had been running around on 92 octane Oregon fuel for a couple of weeks. Our car came up with about 260 Wheel HP and 265 ft-lbs of torque. After installing the Accessport and applying some of the basics to the map we saw pretty awesome gains starting to appear.


Since we have enough experience to know what kind of boost levels we can run on a stock STI, we stuck to those levels of about 19psi at lower RPM and tapered it off to redline. We quickly saw more WHP than we would see on a normal Stage 1 tune from a 2008-14 STI. Only thing that was different is that we really were not able to gain any more power from about 6000 RPM on. No matter the boost or timing, it just didn’t make anymore. Keep in mind this is all done on stock STI. With exhaust system and other mods like an intake, for sure there will be more HP to gain.


After spending about a half a tank of gas tuning, pushing and finding the limits of ignition timing, we did find a few interesting things. As we mentioned before about the laggier turbo, and the fact it was making more HP than older models, we suspected a change to the turbo it self. It is the same turbo part number as found on older cars (VF48), but something seemed different…

Evidence of this can be found with boost levels we can tune to. Older cars is that 14psi at 6500 was always about the most you could get because of the limits of the wastegate  and smaller turbo. On the 2015, I am finding that we can hold peak boost much longer than before and more at redline. The additional 2psi we can run at 5000-5500, really helps make peak power much higher than found on old cars.


The above graph is NOT the normal Cobb Stage 1 map, but a custom map done on our dyno to our specific car. I am only saying that because the results will vary and Cobb’s maps may be more or less HP from here. As you can see, running more boost makes and additional 25WHP and 50ft-lbs of torque. This is exactly what this car needs, just a bit more low end and mid-range grunt.

How does this compare to a Stage 1 from the older STI’s? Besides slight loss of low end power from the slower spooling turbo, it does make more power once on boost, and quite a bit more in the midrange. The 2015 STI really likes more ignition timing is which is why there are pretty awesome gains to be had over previous years.



Tuners Aspect of Tuning the 2015 STI

With most new applications for the Accessport, they always find something that Subaru did that is different. It’s the small changes to maps that already exist or the additional use of maps that were never used before.  During our testing, we found a few small things that don’t really affect HP, but change the tuning strategy.

For boost control related things, there isn’t anything that is different. It’s still Max and Min duty cycle maps as well as the PI controls. Fueling maps are the same, for the most part. Ignition timing maps are where things change. Subaru has simplified the way it does timing, which is great for us. At the same time, one of things we discovered was a new map that affects timing under certain conditions. This is a map that has existed in years past, but was never used. Other than that, the maps are pretty much the same.

Some of the things I noticed during tuning, was how the ECU and engine acted differently than previous cars. For instance, the “Fine Learned Knock” is much more active and changes run to run. You can get some “Fine Learned Knock” then change the base timing (to correct the retarded timing), and the next run it starts to go away. In previous cars it would take much longer and we would end up resetting the ECU. Also our normal AVCS map doesn’t have the same effect as it does on the other cars. I spent a lot of time adjusting the AVCS to optimize spool and power and applying this logic to the 2015 STI (in stock form) doesn’t do anything. Lastly is ignition timing. The stock timing from 5000RPM to redline is highly optimized and there isn’t much to gain. As you can see from the above graph it just poops out from 6000RPM on. This is also why we didn’t run the car past 6500RPM too much as it didn’t make a difference. Again this is on a stock car, and that should improve with a few aftermarket parts.

One last comparison for fun. Below you can see the 2008 STI compared to a 2015 STI, compared to the 2015 STI with a custom tuned Stage 1 map. From old car to new car, you can see that there is a lot to be gained from just a tune. Anyone considering buying a 2014 STI should look at this and really think about how much more fun, and faster the 2015 STI will be with minimal mods.


I am still really in love with this car and can’t wait to start tossing on parts that will make even more HP. The first mod I have planned is one of our equal length headers. Yes, I am not a boxer sound fan, sorry fan boys. I love the smoother, more quiet equal sound our headers provide. Also, they increase turbo spool along with make more power, so that will be a fun first mod to show off.

After that, a catback exhaust, then our cold air intake system. This is a little unorthodox compared to how other people modify their cars, but it will be interesting to see how the header works on a stock car or with a tune. I think with all three of them installed we will easily break 300 WHP and maybe even 320WHP!

One more thing!

So, why does the turbo spool slower?? We are not ready to rip the turbo off the car as we have lots of testing to do, but I did measure the turbine housing in a place that I could easily replicate on a Vf48 from a 2008 STI. I really suspect that Subaru installed a larger AR housing on the 2015 STI. As you can see the boost comes on later, but makes more mid-range and top end power than it did before. This is exactly what we see when swapping to larger turbine housings on our rotated turbo kits.

What I discovered isn’t something that I can say is proof the turbine housing is larger, but this was an accurate and consistent way to check. It’s a pretty small difference, and it could be just a casting change, but the tooling used to make these housings are more accurate than this. I really think this is what changed about these car, but I can’t be 100% sure until I rip off the turbo and measure things. On a side note, Subaru says the part number is the same from 2014 STI to the 2015 STI.