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BrenTuning | 2015+ STi development thread

18K views 31 replies 7 participants last post by  BADBISH 
#1 · (Edited)
Hi guys, new to IWSTI but not new to tuning! We have been tuning Subarus (among many other platforms) for close to 10 years at this point and are happy to finally join this site! We have noticed that the Power Bragging section on this site isn't that active, we are going to bring lots of new content and hope to breathe some fresh air into this section! All of our results are from our in house Mustang MD150 AWD dyno, for reference, stock GR STi's put down around 220WHP and stock VA STi's put down around 250WHP!

Since the 2015 WRX/STi have been released, we have been focusing a lot of our marketing and advertising on the 2015 WRX being that it is all new, but that doesn’t mean we have abandoned the STi. The 2015 STi is very impressive with mods ranging to our typical stage 1 or stage 1+ setup all the way to our stage 3 setup. This thread will detail the cars that come through our shop, the mods that have been performed and the numbers/gains that were found!

Just a quick run down on which parts go with which stage:

Stage 1:

Stage 1 is perfect for someone looking for some extra power, better fuel economy, improved drivability and more safety over the OEM mapping. Our typical stage 1 cars are in the 270-280WHP range with torque around 300WTQ.

- Stock car
- Cobb Accessport
- Stage 1 PROTune

Stage 1+:

Stage 1+ is a great option for those who want a little more power and sound over our Stage 1 mapping. The Cobb SF intake is our intake of choice with which we have found the best and most reliable gains. Other intakes will work, but Cobb provides great products that are well tested, they are always our go to! Expect to see gains of 15WHP/WTQ over our Stage 1 mapping.

- Cobb SF Intake
- Cobb Accessport
- Catback exhaust (optional)
- Stage 1+ PROTune

Stage 2:

Stage 2 is the next step. This includes an aftermarket catted or catless downpipe in addition to an aftermarket intake. A stock intake and catback exhaust can be used with this setup, but to maximize the setup, we recommend an aftermarket intake/catback be used. We prefer the Cobb catted downpipe but there are many alternatives that provide similar results. Our typical stage 2 cars are in the 300WHP/330WTQ range +/- depending on parts selection.

- Cobb SF Intake
- Cobb Accessport
- Catted or catless downpipe
- Catback exhaust (optional)
- EBCS (Cobb preferred)
- Stage 2 PROTune

Stage 2+:

Stage 2+ is for those who are looking to maximize the stock turbo and fuel setup. Any goals beyond this will need additional fueling (ID1000 injectors) as well as a bigger turbo. This will max the stock turbo and place the car in the 330WHP/360WTQ range with many cars being torque limited due to the stock clutch. We have seen cars close to 400WTQ with upgraded injectors, intercooler and EBCS on the stock turbo. Horsepower doesn’t go up all that much but add the above listed mods and you can make more torque if you truly want to maximize your pump gas stock turbo car!

- Cobb SF Intake
- Cobb Accessport
- Catted or catless downpipe
- Catback exhaust
- Equal Length header
- EBCS (Cobb preferred)
- Stage 2+ PROTune

Stage 3:

This is the ideal reliable and discreet stock block setup. With these few mods and a few days at our shop, you can transform your STi into a street monster. We have replicated this same setup for a few customers and they have all been extremely pleased with the results! You’ll get stock like drivability and spool with a massively improved top end. The stock turbo is out of breathe in the higher RPMs, that is where the Blouch 1.5XT-R shines. Top end gains of 100WHP have been seen, this translates to a car that just keeps pulling until redline. Depending on your exact setup we would expect numbers in the 350-380WHP range. This setup can be done on a budget by utilizing the stock exhaust manifold and intercooler, however, we always recommend upgrading both at this power level! For those of you looking to build your block down the road and go for more power, you can opt for the Blouch 3.5XT-R. From our testing we found spool almost identical to the 3.5XT-R, you can find the dyno graph comparison in post #14 of this thread!

- Cobb SF Intake
- Cobb Accessport
- Catted or catless downpipe
- Catback exhaust (optional but preferred)
- Equal Length header (optional but preferred)
- Blouch 1.5XT-R 2.4” 10CM (3.5XT-R optional, 3" inlet required)
- ID1000 Injectors
- DW65C Fuel pump
- Grimmspeed Top mount intercooler (or equivalent; optional but preferred)
- ’07 STi Fuel pressure regulator
- Stage 3 PROTune


Contact:

Email: Sales@Brentuning.com
Phone: 508-762-1769
Facebook: Facebook.com/brentuning
Instagram: @Brentuning



Stage 1-3 Dyno overlay



Stock - Stage 2+ dyno overlay

 
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#2 ·
Stage 1

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Peak HP at RPM: 271WHP @ ~5500RPM
Peak Torque at RPM: 300WTQ @ ~4000RPM
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Target Boost: 19PSI
Target AFR: ~11.0
Fuel: 93 Octane

Contact:

Email: Sales@Brentuning.com
Phone: 508-762-1769
Facebook: Facebook.com/brentuning
Instagram: @Brentuning


Chris brought in his 2015 STi completely stock for us to tune to stage 1. This car came in with 1400 miles, on the OEM fill oil fill and was 100% stock down to the air filter. Chris had the Accessport in the glovebox and had never been flashed. The car baselined very low compared to the other 2015 STi’s that we have had in the shop at 236WHP/217WTQ. We only did one pull on the stock map, it is possible with a few more pulls the power could have been higher. After putting our map on and making a some pulls to optimize the map, we achieved final numbers of 271WHP/300WTQ! Timing was kept lower than normal per the customers request, there was some power left on the table for sure.

 
#3 ·
Stage 2

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Peak HP at RPM: 306WHP @ ~5750RPM
Peak Torque at RPM: 336WTQ @ ~4250RPM
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Target Boost: ~20PSI
Target AFR: ~11.0
Fuel: 93 Octane

This 2015 STi came in for a Stage 2+ tuning. The car baselined 279WHP/297WTQ on our in house Mustang Dyno with Cobb OTS Stage 2 mapping. After spending time on the dyno honing in the map, we found the best combination of power and reliability. The cars final map came out to 306WHP/336WTQ with a safe and reliable 10.9-11.0AFR and only at 20PSI.

 
#4 ·
Stage 3

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Peak HP at RPM: 370WHP @ 6350RPM
Peak Torque at RPM: 350WTQ @ ~4650RPM
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Target Boost: 20PSI
Target AFR: ~11.0
Fuel: 93 Octane

Vito came to us with his 2015 STi for us to build him a perfectly reliable, quiet, powerful and emissions friendly daily driver. The mod list is very simple and that was the goal, keep everything is basic as possible while still making reliable power on the stock longblock. One of our favorite turbos at BrenTuning is the Blouch Dom 1.5XTR. This turbo provides basically stock like spool with amazing gains throughout the whole rev range and a massively improved top end. As you can see in the graph below, spool is almost exactly the same as our stage 1 tune on the same car with gains of over 100WHP at redline. As far as the tune on this car, it is at 20PSI with AFR at 11.0. Timing was kept low and the car was built with reliability and longevity in mind. We could definitely pushed the car further and made higher numbers, but there was no need. This setup is quick enough for a daily driven street car!

This is the ideal setup for the street and this package can be easily replicated. If you are looking to do something similar on a lower budget, you can go with the stock exhaust manifold or a different EL header, we do really like the KillerB header and definitely helps complete the package and keep spool the same as stock! The car has a Cobb catted DP which tapers to 2.5" and a Corsa Catback which keeps everything fairly quiet for a 370WHP car. No sensors have been messed with, the stock clutch and inlet were used and the car is still on MAF.

Baseline stock: 252WHP/245WTQ
Stage 1 Protune: 271WHP/270WTQ

Contact

Email: Sales@Brentuning.com
Phone: 508-762-1769

Mods

- Stock longblock, Stock clutch, Stock inlet etc
- Blouch Dom 1.5XTR 2.4" inlet 10cm Hotside internally gated
- KillerB Holy Header
- Grimmspeed TMIC
- Cobb SF intake w/ Box
- Cobb Catted DP
- Corsa catback exhaust
- ID1000
- '07 STi FPR (fuel stumble)
- DW65C Fuel pump
- KillerB Pickup tube
- Cobb Accessport







1.5XTR vs BrenTuning stage 1





 
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#5 ·
Here is an interesting comparison! While this is a GR WRX vs VA STi, it really shows that the bigger Blouch turbos don't compromise spool. We installed a 3.5XTR on a low mile '11 WRX with basically an identical mod-list to the "Stage 3" '15 posted above. The biggest difference would be the KillerB header ('15) vs Agency Power EL ('11). The 3.5XTR is only at 18PSI and the 1.5XTR is at 20PSI. Power numbers are almost identical while being at lower boost levels with negligible difference in spool. The 3.5XTR is really a great option for those of you who would like to shoot for more power down the road while still having a very streetable stock block car!

 
#6 · (Edited)
Stage 1+

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Peak HP at RPM: 301WHP @ ~6150RPM
Peak Torque at RPM: 318WTQ @ ~3950RPM
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Target Boost: ~19PSI
Target AFR: ~11.0
Fuel: 93 Octane

Ian came to us with his beautiful bagged '15 STi for a PROTune! The car came in equipped with a Cobb SF intake and Invidia Q300, nothing else. We have tested most of the intakes for the '15 on the market and always find that Cobb performs the best. It is the most consistent and always seems to make the best numbers, also great quality and fitment is perfect as you would expect from Cobb. This car put down an easy 301WHP and 318WTQ which makes for a great, reliable DD!

Stock vs Stage 1+





 
#20 ·
Update from post 6 :)

Stage 1+

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Peak HP at RPM: 301WHP @ ~6150RPM
Peak Torque at RPM: 318WTQ @ ~3950RPM
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Target Boost: ~19PSI
Target AFR: ~11.0
Fuel: 93 Octane

Ian came to us with his beautiful bagged '15 STi for a PROTune! The car came in equipped with a Cobb SF intake and Invidia Q300, nothing else. We have tested most of the intakes for the '15 on the market and always find that Cobb performs the best. It is the most consistent and always seems to make the best numbers, also great quality and fitment is perfect as you would expect from Cobb. This car put down an easy 301WHP and 318WTQ which makes for a great, reliable DD!

Stock vs Stage 1+





 
#7 · (Edited)
Stage 2+ FlexFuel

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Peak HP at RPM (91): 315WHP @ ~4700RPM
Peak HP at RPM (E72): 348WHP @ ~5350RPM
Peak Torque at RPM (91): 347WTQ @ ~4700RPM
Peak Torque at RPM (E72): 402WTQ @ ~4200RPM
Target Boost (91): ~20PSI taper to 16PSI
Target Boost (E72): ~21PSI taper to 16.5PSI
Target AFR (91): ~11.1 taper to 10.9
Target AFR (E72): ~11.7 taper to 11.1
Fuel: 91 and E72 (FlexFuel)

We had a stage 2 + EL header 15 STi some in the other day for some FlexFuel love! The car had 91 octane in the tank since it is getting shipped to Arizona in a few months. The car is ridiculous on E72 (NE winter blend) making over 400WTQ. The FlexFuel kit is very complex but works flawlessly. I can definitely understand why there was a such a delay in launching it. Cobb never releases something that is less than 100% perfect.

Modifications include:

COBB 1000cc injectors
Aeromotive 340LPH fuel pump
Invidia EL header
Grimmspeed up-pipe
Grimmspeed limited catted downpipe
Invidia Q300
Cobb SF W/ Box

 
#15 ·
The difference in lag over stock is noticeable but it's still very much an easily daily driven street setup. It's not laggy like many of these big cam rotated cars that don't open up until 6K+, but it is laggier than stock. The car will spool quicker on the street than what the dyno shows. Shifting close to redline will put you into the powerband for the next gear so depending on shifting quickness and if you use FFS, drop-off between gears may be non-existent.

Compared to a stock car they make the same torque at 3700RPM.
Compared to a stage 1 car they make the same torque at 4100RPM.
Compared to a stage 2 car they make the same torque at 4300RPM.

Chris@BrenTuning
 
#21 ·
Let's bump this. We had two 2015 STi's come in yesterday with the same mods list. Catted turboback exhaust and Cobb SF intake were the common parts. The big difference was that one had an upgraded fuel system with ID1000 injectors and a DW65C pump and the other was on stock fueling. As many of you know, the 2015 STi maxes the injectors at power levels beyond stage 2, this is why Cobb does not offer their Stage2+SF mapping like they have for previous model years. While Cobb does not offer an OTS solution, we can tune the car safely with IDC at a safe level even on stock fueling. With stock fueling, the power just has to be scaled back a bit.

While peak numbers aren't huge, the midrange gains are 15WHP/20WTQ throughout. Additionally, if you plan on upgrading your car further down the road, you'll be all set!

Contact us for your Injector Dynamics / DeatschWerks fuel system upgrades!

 
#22 ·
I brought my 2015 STi to BrenTuning recently for a protune and I'm very satisfied with the results! Everyone was friendly and knowledgable. After the tune I felt like I was driving a different car. I'm glad I brought my STi to you guys.

I'll be contacting you guys in the future for that upgraded fuel system. ;)

Many thanks to BrenTuning!
 
#23 ·
Hey Kai, glad you are happy, and the ID1000 setup is definitely a good next step, especially if you want more mods down the road.

And for those of you who were curious, IDC on the stage 2+SF stock injector car was right around 95% at the top of 4th gear. On the ID1000 car, the IDC was around 60%. As for tuning differences go, you have to run a leaner mixture and taper the boost up on the stock fueling car, with ID1000 you can run a bit more timing and boost.

Chris@BrenTuning
 
#24 ·
I had my car retuned by Bren today. He had tuned it previously with no mods, car made 286/306. i bought a Cobb Sf intake from a fellow member, after Bren recommended it as being consistent and reliable. Had to retune for the intake, Bren got 301whp out of it today (heat was a slight issue today, 115degree intake temp) after he let it cool down he got the number he knew i was looking for. Drove home and all i cay say is, WOW!!! He mentioned that spool was 500 rpm sooner, doesn't sound like much, but it really is. Took me by surprise the first time, lol.

I'm a pretty picky guy, as some that know me will attest... I can't say enough good things about Bren and his crew there. I feel comfortable there, like they are old friends. They've instilled a confidence in me that they are going to treat my car like it was their own, and treat both it and myself with respect. Brentuning is the only place i'll be going for my STi needs... and hopefully soon... my GT-R. Thanks again guys for another job well done, happy customer here!!
 
#26 ·
Our customer Mark just had us take his car from protuned stage 1+ SF all the way to 400+WHP on the stock block in the course of three short days. The car is extremely streetable with similar manners to OEM and was built and tuned with reliability in mind. Torque is matched 200RPM later and makes 150WHP more on the top end. The engine bay doesn't look any different than stock and you would never know from the outside that it is 400+WHP. Below is a graph of stage 1 vs 3.5XTR on pump gas vs 3.5XTR race tune. There is plenty of power left on the table for when he decides to upgrade the block down the road.

Build consisted of:

- Blouch 3.5XT-R 10CM
- GrimmSpeed Black TMIC
- ID1000
- Cobb FPR
- Invidia catted DP
- Perrin Catback exhaust
- Exedy clutch
- DW65C Pump
- IAG TGV Deletes
- Agency Power UEL Header
- GrimmSpeed UP
- Cobb EBCS
- Stock block

I am probably forgetting a few things, he also has every Cusco chassis brace you can get, LCA's, brakes, springs and much much more. VERY nice build! We will be sure to post back when he upgrades the block and we turn the wick up more!


 
#29 ·


Ian came back for more tuning after installing another round of modifications. As seen in post 6, he previously had a Cobb SF intake and Invidia Q300 catback and posted some very strong numbers for a stage 1+ car. This time he added:

Catless Downpipe
KillerB EWG Header
Tial 38MM EWG
DW65C
ID1000

This is basically our ideal stock turbo setup and could put a hurting on many other upgraded turbo cars. The KillerB header proved to make 30WHP/30WTQ over every other similar (stock manifold) setup we had done prior. While they are pricey, the performance speaks for itself.

Below is his stage 1+ setup we tuned a few months back vs the current setup. Notice the boost curve and that the car is at a lower boost level while making 30+WHP/45WTQ more. This is on 93 octane in 85*+ weather, previous tune was done in winter.



Chris
 
#31 ·
Funny you ask, I was going to update it today!

Stage 2+ FlexFuel

Car: 2015 STi
Tuner: BrenTuning
Dyno Info: Mustang MD150
Transmission: 6-Speed
Gear: 4th
Baseline HP/TQ for stock on same dyno: 2015 STi - 250WHP/250WTQ
Peak HP at RPM (91): 315WHP @ ~4700RPM
Peak HP at RPM (E72): 348WHP @ ~5350RPM
Peak Torque at RPM (91): 347WTQ @ ~4700RPM
Peak Torque at RPM (E72): 402WTQ @ ~4200RPM
Target Boost (91): ~20PSI taper to 16PSI
Target Boost (E72): ~21PSI taper to 16.5PSI
Target AFR (91): ~11.1 taper to 10.9
Target AFR (E72): ~11.7 taper to 11.1
Fuel: 91 and E72 (FlexFuel)

We had a stage 2 + EL header 15 STi some in the other day for some FlexFuel love! The car had 91 octane in the tank since it is getting shipped to Arizona in a few months. The car is ridiculous on E72 (NE winter blend) making over 400WTQ. The FlexFuel kit is very complex but works flawlessly. I can definitely understand why there was a such a delay in launching it. Cobb never releases something that is less than 100% perfect.

Modifications include:

COBB 1000cc injectors
Aeromotive 340LPH fuel pump
Invidia EL header
Grimmspeed up-pipe
Grimmspeed limited catted downpipe
Invidia Q300
Cobb SF W/ Box

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