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2015-2021 WRX FA20 Mod Guide

These are the typical results you can expect when modifying your 2015-2021 WRX. We started with a completely stock FA20 WRX and did 4 stages of modifications. We kept track of the results to show you the comparisons. All of these results are uncorrected numbers which are 20-25% lower than you would expect to see on a Dynojet dyno or our “Shootout” numbers. For more information on comparing dyno numbers check out our dyno page.

Our starting point was completely stock. With no tuning, no modifications, and with 91 octane fuel.

This vehicle made 180 HP and 210 FtLb TQ on our Dyno at 15psi tapering down to 10psi by redline. The factory rates these cars at 268 HP and 258 FtLb TQ at the crank.

Below you find the information of our findings along with dynographs for comparison. If you have any questions about building your 2015+ WRX , give us a call (763) 316-5882.

Stage 1 vs Stock

This included the Cobb Accessport and no modifications on the same fuel as our stock vehicle. We performed a custom tune and these are the results.

This stage we made 202.5 HP and 241.5 TQ on our dyno. We saw a 21 HP or 12% increase in peak HP and 32 FtLb of TQ or 15% gain in TQ over stock. We were able to get a good 10-20 HP increase through the whole powerband.

Click here to check out our Stage 1 Custom E-Tune Package.

Stage 2 vs Stock

This included the same fuel from our stage 1. We removed the 2nd restrictor pill and added a Grimmspeed J-pipe and Intake.

This stage made 232.0HP and 252.1FtLb TQ on our dyno. With stage 2 we found a 52HP or 29% increase in peak HP and 42FtLb TQ or 20% gain in TQ over stock. We saw gains throughout the whole powerband increasing to a maximum of 81HP at 6300rpm. You can expect 5-10hp more on 93oct.

Click here to view our  Stage 2 Custom E-Tune Package. 

Recommended J-Pipes

  • Grimmspeed–  The V2 GESi Catted J-Pipe is the only J-Pipe that wont throw a P0420
  • Cobb

Recommended Intakes

  • Grimmspeed– This intake functions the best from car to car. Other intakes can read differently simply by installing the air filter in a different location then the original spot.

Stage 2+ vs Stock

This included the same items and fuel from our stage 2. Additionally we installed a Grimmspeed electronic boost controller, charge pipe, and most importantly a top mount intercooler.

This stage made 250 HP and 265 FtLb TQ on our dyno. With stage 2+ we found a 69 HP or 38% increase in peak HP and 55 FtLb TQ or 26% gain in TQ over stock. Upgrading the factory intercooler to the Grimmspeed intercooler is one of the best modifications you can do on these vehicles. With the factory intercooler we were seeing manifold temps peaking between 130-150 deg F by 6500 RPMS. With the Grimmspeed intercooler we commonly only see 5-10 deg increase compared to the 30-50 deg we see with the stock intercooler. This was nearly 30 HP increase from the Grimmspeed intercooler.

Recommended J-Pipes

  • Grimmspeed–  The V2 GESi Catted J-Pipe is the only J-Pipe that wont throw a P0420
  • Cobb

Recommended Intakes

  • Grimmspeed– This intake functions the best from car to car. Other intakes can read differently simply by installing the air filter in a different location then the original spot.

Recommended Intercoolers

Recommended EBC 

Stage 2+ E60 vs Stock

This included the same items as our stage 2+. Additionally we added a Cobb flex fuel kit,  Detsch Werks fuel pump, and put the vehicle on 60% ethanol.

This stage made 310 HP and 305 TQ on our dyno. With stage 2+ E60 we found a 128 HP or 71% increase in peak HP and 89 HP or 42% gain in TQ over stock. We purposely keep the wheel torque around 300ft/lbs to help protect the weak rods in these engines. We saw gains of around 80 HP at 3500 RPMS climbing up to around 150 HP at 6400 RPMS over stock. We saw about 60 HP in peak power from stage 2+ to stage 2+ with E60 with no changes in boost.

Click here to check out our custom E-Tune Flex Fuel Package.

Recommended J-Pipes

  • Grimmspeed–  The V2 GESi Catted J-Pipe is the only J-Pipe that wont throw a P0420
  • Cobb

Recommended Intakes

  • Grimmspeed– This intake functions the best from car to car. Other intakes can read differently simply by installing the air filter in a different location then the original spot.

Recommended Intercoolers

Recommended EBC 

Recommended Flex Fuel Kits

  • Cobb- No longer available as of 4-18-2022
  • Delicious Tuning– The delicious kit can be optioned with a LPFP (low pressure fuel pressure) sensor. With this sensor you can monitor LPFP on the Accessport and the Delicious kit will signal the ECU to put your tune into a limp mode if LPFP drops below ~35psi.

Recommend Fuel Pumps

Have Questions? Call Today!
(763) 316-5882