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As you know we have been busy fitting parts, re-designing parts, and coming up with completely new parts for the new STI and WRX for a few weeks now. It’s time to get on with the pictures and commentary some of you have come to expect from us every time a new car comes out.

Where's the FA25DIT!!

I have been dying for a new car from Subaru for a long time. It had been since 2007 (Model Year 2008) since Subaru launched something really new. Like many people, when they launched the new cars, I was let down by the STI due to the fact that it had the same power plant and drive train as the previous years. I suspected the drive train would be the same bombproof setup, but come on, the EJ engine!!! Subaru sold us on its best handling, fastest blah blah blah. Sounds great and all, but I wanted a new FA25 DIT, where is this! Even if my initial thoughts are negative, Subaru is smart. Keeping one of the two new cars using the same basic power train, allows the aftermarket world to get ahead of the game and offer some parts for the cars right away. Secondly this allows all the motor sports teams to be able to have a program from the launch of the car. Both are important to keep the whole tuner and enthusiast market alive and rockin’. Had Subaru done what most of us wanted (Make the STI with a FA25DIT engine), this would have really put a damper on Subaru’s motor sports teams being competitive right away. So I get it, but I still WANTED A NEW ENGINE!!


Initial Thoughts

Initial thoughts before I even drove them or sat in them – Which car do I like? What car will be the most popular one? I want the WRX engine in the STI. That would make me happy. Knowing that won’t happen, I initially am more excited for the WRX. The WRX is the bread and butter of our world, where the STI is still a rather limited car and limited customer base. So for me, the WRX was what I was drawn to. Yet, I still bought an STI for myself, why is that?


Well, the STI is still my car of choice for a few reasons, most of which are non-drive train related. Yes it has the more powerful engine, but it’s all the rest of the things. The brakes, the nicer wheels, the wing, and probably the biggest thing which makes me the happiest to see every day is the interior. The Alcantara seats, the door panels, the red stitching, and red accents make the interior amazing. It’s the one thing I see and touch every day that makes me really love the STI more than the WRX. I made this choice without even seeing either car and as long as someone can afford the higher priced STI, I think they will be equally as happy with their decision.

Why STI over the WRX?

Now that we have received both cars and I have driven both, I can say that I stand behind my decision. The interior of this car is amazing compared to all the other Subaru’s I have owned. The $200-300 more that Subaru spent on it, absolutely shows! Even the WRX interior is far better than it was before. The cloth interior and panels on the doors looks really nice, along with both cars having the flat-bottomed steering wheel. Both the 2015 WRX and STI are a huge step up over the older cars.


As you can see, from the driver’s point of view, the cockpit is far nicer and that flat-bottomed steering wheel is very “race-car” like. The only difference in the WRX and STI steering wheels is the STI has the perforated leather side panels compared to the WRX’s smooth leather.


Both cars share the same dashboard with the fake carbon fiber inlays. Even though this is fake, it is probably one of the best looking fake carbon fiber parts out there. It’s still not everyone’s favorite, but it’s a huge step up over the FR-S interiors carbon fiber looking parts.



The actual gauge cluster found in the STI and WRX share the same basic construction with the super nice bright faces with white needles. This has become the standard for Subaru, instead of only offering this in the STI models. Again, this really makes the WRX stand out a lot more, and not feel like such a downgrade.


Another feature shared between both cars is the center display located in the center of the dash. Most WRX fans will love the fact that is has a factory boost gauge with peak boost readings in a super easy to read display. There are other displays to scroll through like MPGs (both instant and trip versions), a clock, a graphic showing the AWD system working, and a few others. As most all customers will find, they are all pretty much useless and the boost gauge is what you will leave it on; no one wants to know your MPGs after driving these cars, as you will find it’s never very good as it’s hard to keep you foot off the gas

Below is a side-by-side comparison of the interiors all shot from the same angle. They will all go in the order of the WRX, STI, then STI Launch Edition package.

From Right Side Looking In....




Door Panel From a Few Feet Back...




Close-up of Door Panel Material...




It is hard to tell in the pictures, but the WRX cloth is very nice and really isn’t a turn off. A few of us at the shop have owned a WRX in one form or fashion and we all think the same thing in that the 2015 WRX interior is really awesome, but the STI interior is even better!

Physical Differences in the WRX and STI

The most obvious difference between the cars is the engine. But the more interesting things are the little items that changed between the cars. This is one of my favorite things to do, poking around to see what is different, taking notes on things, taking pictures to help with future development on parts and it helps satisfy my curiosity.

Since Subaru changed the wheel bolt pattern on the WRX, I wanted to see if they changed the offset or anything else important about the wheels. Both cars have the same tire, just one is a 245 and the other is a 235.


You can see that the WRX wheel size and offset is the same as it has always been. The good news is that there is a lot more room for bigger wheels and tires. The included tires are actually pretty decent summer tires with a nice low tread wear rating, showing they are a pretty sticky for the kind of driving we like to do.


Both the STI and WRX now have available LED headlights. At night these lights are amazing, and by far the best headlights ever installed in a Subaru. They light up the road perfectly with only one issue: the high beams and fog lights (if equipped) are halogen. That means when you hit the high beams, or turn on the fog lights, everything looks really yellow. The only bummer is the WRX doesn’t come with the LED lights, only the WRX Premium and higher levels do. For the first time in the US, Subaru has installed an auto-leveling headlight system. Since 2004, customers have asked us about the tab or holes on the rear left control arm. Customers would think they are missing a part or something fell off, which is pretty funny. So, gone is the typical rolling type button to adjust the lights up and down.


Since the STI shares the same engine as the older car, it also shares the same type of steering rack. The STI’s hydraulic assisted steering rack (13.0 Ratio vs. 2014 had 15.0) and the WRX (14.5 ratio)


All STI Models come with the heated windshield and side mirrors as standard, whereas the WRX you have to step up to the premium model or higher before you get that. It’s a minor feature but still a cool one. You can see in the below picture how they removed the washer nozzles from the hood and moved them down to the plastic cover. I love this as it makes washing the hood easier and look much nicer.


Because the WRX has the FA20DIT engine with the turbo mounted down low, there are a few things chassis-wise that are different between the STI and WRX. The most noticeable thing is the lower splash guard hangs down lower by roughly 1.00″. You can see the picture below and how there is a large bulge in the middle as well as the two outer areas on the WRX.


With the plastic splash guard removed from the WRX, you can see further bracing as well as another panel to be removed. The two large braces you see in the picture below act as a skid plate to keep the turbo and other vital engine parts protected during an “off-road” situation. These braces are actually an aluminum forging, and are actually pretty nice.


While I was down there poking around, I noticed something pretty interesting. The front 02 sensor has 5 wires. This indicates that is a wideband type 02 sensor, which isn’t new for Subaru turbo cars to have on the front sensor. The difference is previous cars had a 4-wire type, which was accurate in the normal operation range of the engine, but not accurate under full throttle. This new sensor looks to be one that will read accurately to the rich side of things and may be able to replace the need for aftermarket wideband 02 sensors.


This is one of the other differences in the WRX compared to the STI. It’s one of those things that has to be different because of the engine that is in the WRX, and I chose to take a picture because this is what the “downpipe” looks like for these cars. Since the turbo is mounted low and exits the bottom of the car, the downpipe has to pass under the subframe and still clear the ground, hence the reason for the flattened portion of the pipe! From this you can see there is some decent improvement to be had in the exhaust system coming right off the turbo. It may be a little tight fitting a 3.0″ tube there and still have ground clearance on cars that are really slammed.


There are a few other little changes because of the new engine, which you will see over time from us in a future post on new parts we start to come out with.

Changes for the Better

Anytime a new model comes out, we all hope Subaru listened to us and made things better. Well they have! Subaru has done a lot of little things that all add up and make their cars that much better!

We all like to put on wider wheels and tires as well as lower the car (sometimes too much) and there are always limits. Subaru has watched how we all end up rolling fenders (or let the tires do the rolling for us) and they have finally gotten rid of that huge lip in the rear fender. As you can see, they removed the area that always rubbed and always need to be modified. The removal of this lip saves us all tons of time in not have to roll fenders or cut sheet metal. A benefit of Subaru doing this is that 275 wide tires will easily fit on this car as shown below.


Below is a great example of a 275/30/19 on a 10″ wide wheel using a 38mm offset. This is a pretty tight setup on slammed car, but it fits the look that many people are going for these days. A perfect setup would be this with a 45mm offset. As you can see, it sits very flush with the fender and looks really good as is.


Normally we see these flat panels on special JDM models of the STI and WRX, but now they come on the US spec. cars! There has always been a front splash guard on the WRX and STI, and now they have added all the side panels.


As you can see, the side panels cover the normally ribbed and hole drilled frame rails, which created disruption in airflow under the car, which ends up creating noise. The bigger benefit for us enthusiasts is the bottom of the car is more aerodynamic which does help with better downforce on the car at high speeds.


This is another small detail that Subaru has done to make this car quieter, and when you add up all the things, it’s no wonder why it’s so nice cruising down the road.


The rear suspension appears unchanged, but it has been for the better; the upper control arm is not a heavy cast iron part, but rather a thinner sheet metal version. Smart on Subaru’s part to help reduce the weight of the car and probably reduce cost. More importantly, the rear suspension is based off the BRZ rear suspension with a shorter trailing arm and I am sure some minor changes to locations of the suspension pivots.


On the front suspension it appears as though a few things were the same, but that also isn’t the case. Once only found on the 2011+ STI, the front control arm rear bushing with spherical bearing is now on both the STI and WRX. This bushing has much less deflection than the older style bushing and significantly reduces the amount of deflection in the front wheels under braking. They have moved the bushing down to remove some of the anti-lift geometry built into the car. This is something we have been doing with our PSRS kits for years!

The other most obvious thing is the extra brace that connects the lower portion of the subframe to the rear portion of the chassis. This added brace along with an even beefier lower control arm bushing mount brace really helps lock down the front end of the car.


Just like the added bracing to the front of the car, there is added bracing to the rear. Now there is a really simple, but effective, bar that ties the mounting points for the rear subframe to the chassis even better. This bar attaches at 6 main points across the spare tire well and outer frame rails. Customers with 2014 or older WRX’s and STI’s will NOT be able to put this on their car without a bunch of drilling and welding.


For those of us who are bleeding brakes all the time, you will love how the clutch master cylinder reservoir is now merged with the brake master cylinder reservoir. It’s not a huge improvement, but it really cleans up the engine bay.


How do they drive?

After driving my STI for a solid week and having a few back road track days, I was very familiar with how the STI handled and worked. I found the limits of the car and felt really confident in how it performs. Probably the biggest change is how much flatter the car is around corners and how the Torque Vectoring system works. It is amazing how much difference this makes in the car going around really sharp corners, or when you do really stupid things with the car. Some might be wondering what this system really is or how it works; it’s very simple in how it works and very complicated in how Subaru makes it work. If you think about when you go around any corner, all four wheels turn at different speeds. The Torque Vectoring system works simply by keeping the wheels at the proper theoretical speed through the corner by applying the brakes (and sometimes reducing engine power) to control the car. This means, it goes were you point it! A very cool system that first came to light on a few high powered front wheel drive cars where application of power in a corner typically resulted in understeer. Typically AWD systems create the same understeer type scenario under power. Subaru’s torque vectoring system significantly reduces this along with putting more engine torque to the rear (41:59 Front to Rear) it completely changes how the car feels going around corners.

Are there any quirky things about how the STI drives? Since no car is perfect, there are a few minor issues I can gripe about. The one thing I really dislike is the SI-Drive settings. On the older cars, “I” mode was way too lazy on the throttle, meaning it took a lot accelerator pedal use to get it out of first gear. On the 2015, the “I” mode is setup exactly how I would want it with nice power modulation. The gripe lies with the other modes. “S” mode is pretty twitchy feeling which makes 1st gear a little rough and part throttle provides a decent amount of boost. Then “S#” mode is out of control! It is way too twitchy in 1st gear and crazy boost at part throttle. I tried driving the car on the edge in this mode and it’s very hard and not smooth. So I have come to HATE the SI drive button and can’t wait to change it’s tuning so all modes at least feel the same! The only other thing to criticize about the way the car drives, is that I really wish it had more low-end power. Coming from a much higher HP car and my other STI, I must be spoiled. Understanding that with a tune and an exhaust system this will be fixed, but I really wish it had a bit more power from 2500-3500 RPM.


With all my seat time in the STI, it was easy to be able to figure out how the WRX would compare with taking it out for a nice 45 minute drive. Initially, the WRX feels snappy and faster, but then you quickly realize that it feels this way only because of how Subaru has programmed the throttle to act. Like many new cars, the ECU is programmed to make the car feel torque-ier than it really is by changing the pedal to throttle relationship. In a normal situation, if you were driving the car with your foot pressing halfway down on the accelerator pedal, you expect half the power or so. When pressing the pedal to the floor, you continue to get more power. Same goes for pressing the pedal down say 25% during normal light-load situations. Car companies have been slowly changing the relationship of the accelerator pedal to throttle making 50% pedal equal to 100% throttle. What this means is when you press the accelerator pedal down 50% it’s actually as though you have the car floored and as you press the pedal down more, there is no more power. This is exactly what Subaru has done on the WRX! This is what makes the car feel snappier, and have more torque at light throttle; it’s because at 10% accelerator pedal position, the throttle is close to 50% open! It really comes to light when you are driving the car hard at part throttle though a corner, then you come out of the corner and give it more throttle and there isn’t anymore power. It’s not that the car is slow at all, it’s just that there isn’t that smooth application of power where half throttle means half power. Car companies have been doing this for a while now and normal people really like it as it makes the car feel faster. But to me and other people that are more “driver” oriented, this is very annoying.

With my major issue with the WRX out of the way, we can hit on some of the positives. The engine is very, very smooth and also very quiet. In fact it’s so quiet that Subaru removed one of the resonators on the exhaust to help make it louder. The sound from the exhaust is still pretty mellow compared to the STI which is actually a good thing. I am not a boxer rumble fan as exhausts are always boomy and loud until you install an equal length header on an STI. The WRX starts out with an equal length header as well two large cats that help keep the noise down. Since Subaru changed the engine to the new FA style with the chain driven cams, the actual noise coming from under the hood is much less. We also discovered that Subaru had added more sound deadening material to the doors and other parts to help keep the noise down. This is a small detail that just adds to how much nicer these cars feel and sound while in the driver’s seat.

The power from the engine itself is very good; it feels almost the same as the 2.5L EJ engine in the STI up until about 4500 rpm. Since most people drive their car in that range anyway, it’s not power you really miss until you start pushing the car hard. Shifting both cars at redline really allows you to notice the lesser power after 4500 RPM. Shifting the WRX at lower RPM actually feels better because it lands in the meat of the power band. Either way, the WRX is not slow by any means, and on our dyno, it makes the same wheel horsepower as the 08-14 STI’s do. So that tells you something!


Below is the boost curve found on the WRX and STI.


As you can see from the dyno graphs, the STI does make more power (a lot more than it did before), but the WRX is more responsive. Being that the WRX is a smaller engine, you wouldn’t think this, but it’s due to its new lower mounted turbo (closer to the engine, as well as new longer stroke engine). The turbo may be sized slightly smaller as well, but we haven’t dug this far into it yet.

One thing about the WRX that is better than the STI is that they have a much more solidly mounted steering rack. When looking over both cars and seeing what parts fit and which don’t, the PERRIN Steering Rack Bushings were one of the things we tried to fit. Very quickly we found they don’t because of the completely different steering rack. We tested to see how soft the bushings are using a pry bar against strategic points and we found virtually ZERO movement! This is great as it is one of the things that helps make these cars steer more precisely than before. Even if the steering ratio is slower than the STI, the overall feel of this car is very, very good and far better than previous models.

How does the WRX handle? In the corners you can feel the slightly smaller, less grippy tires come into play as well as the softer suspension. Even with it not feeling quite as solid, the Torque Vectoring System really pulls the car through the corners and points the car where you tell it. I really feel like this new system they have employed on these cars is what makes the 2015 WRX as good as everyone says it is. It’s surely a major step forward compared to any other WRX that has come out. In fact, I would say that it’s better than almost any past STI…

So handling-wise how does this compare to the STI? In a comparison from stock to stock, for sure the STI is better. It’s more solid feeling and the STI’s quicker steering rack is what makes it far superior. Yes, once modded both cars will handle the same, but the “feel” of the STI will always win with that quicker steering rack.


Few last notes about the WRX. Shifter in WRX is weird and loose. You can put it into the 1/2 gate, and the shifter moves left to right quite a bit. It also seems to have a super short distance between the 3/4 gate and the 5/6 gate. It’s just weird comparing it to the STI 6spd tranny, which is one of the best shifting trannys around. One last thing, the steering rack in WRX has a rubber dampener that reduces the feedback to the driver. You can feel that the dampener comes into play when you turn left to right fast or in a parking lot where you are maneuvering the car. In track day situations, I think this part will become very noticeable and something people will be looking to fix ASAP. Both of these issues are things we plan on solving with parts we will be making.

Conclusion on the driving and power aspects of the cars – The STI is better handling mainly from the drivers feedback of the quicker ratio steering rack. The overall handling difference in the corners is very similar, but the WRX feels a bit softer. Other than that, once both these cars see some aftermarket suspension, it will be really hard to say one is better than the other. Both cars have plenty of power to make who drives them grin. Of course we all want more power, or smoother power, or extra features, but I think most people who buy these cars will find that there is plenty of power on tap until the aftermarket world catches up.

What Parts do we make and what parts are we going to make?

It’s amazing how many parts fit that we already have. Knowing that this is a different chassis, different engine (on the WRX) and then the interior being very different, we expected almost nothing to fit. For the STI almost all engine parts we make fit perfectly. There isn’t really anything that needed changing except for a couple instructions needing to be updated. The drivetrain on this car is also the same, which means all the engine mounts, tranny mounts, shifter bushings and other drivetrain related parts, all fit. It’s almost easier to say what doesn’t fit. Front sway bar and front endlinks are different and require redesign. The front mount intercooler needs a total redesign as well; this is due to the bumper and routing of tubes needing to change. Other than that for PERRIN performance related parts, the STI doesn’t have many other items that need to be redesigned.

One of the first items we put on our car was the catback exhaust. Our system fits perfectly due to the way the center section is adjustable. This does fit on both WRX and STI.


One of the more surprising things to fit was the strut bar. Surely Subaru would have moved the strut towers for this new chassis… nope they left them the same!



The WRX on the other hand is where some of these things change. There are a ton of parts we have that will work but also a bunch we will need to remake. The PSRS requires some new spacers (same story for STI), our water pump pulley needs to be smaller, intake system needs a complete redesign as well as the front mount intercooler, front sway bar, and front endlinks. Other staples of our line up are drivetrain related things like steering rack bushings, short throw shifters, shifter bushings and things that like. Since all these items are different, all of them need to be redone. There are other goodies that we will be making as well, but we can’t show you all our cards!


This is absolutely the best STI and WRX Subaru has ever delivered to the US. It is amazing in how it handles compared to the old car, amazing in the quality of the interior, I love the looks, I love almost everything about it. How much do I love it? In 20 days I had put 1500 miles on the car, which shows how much I love it! Since I picked it up, I have driven this car far more than any other car I have owned. I have beat the living crap out of my car and it just makes me happy every day I drive it. If people can get over the looks, I think anyone who owns this car will be happy and probably keep it longer than any other car they have owned.


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