2015-2021 Subaru WRX STI Mod Guide
2.5L H4 EJ257 (EJ257) • 310 HP / 290 lb-ft • Turbo • AWD
Best Performance Mods for the 2015-2021 Subaru WRX STI
Looking to get more power out of your Subaru WRX STI? We've cataloged 18 performance parts across 7 categories with real-world HP and torque gains.
The biggest single gain? The Cobb Cobb AccessPort Tune (Tune/ECU Flash) adds +40 HP on its own.
Intake
Cold air intakes, short ram intakes
Cobb Cobb SF Intake
Cobb Tuning Products Cobb Tuning Products 715160: COBB Tuning SF Air Boxes
Cobb Tuning Products 715160: Air Filter Box, SF Intake Air Box, Aluminum, Black Powdercoated, Subaru, STI, Kit - COBB Tuning SF Air Boxes add the benefits of a cold air intake to the outstanding perfo
Cobb Tuning Products Cobb Tuning Products 716100: COBB Tuning SF Air Boxes
Cobb Tuning Products 716100: Air Filter Box, SF Intake Air Box, Aluminum, Black Powdercoated, Subaru, STI, Type RA, Kit - COBB Tuning SF Air Boxes add the benefits of a cold air intake to the outstand
Exhaust (Cat-Back)
Cat-back and axle-back exhaust systems
Mishimoto Mishimoto MMEXH-WRX-15: Mishimoto Subaru WRX/STI Cat-Back Exhausts
Mishimoto MMEXH-WRX-15: Exhaust System, Cat-Back, Single In/Dual Out, Stainless Steel, Natural, Split Rear Exit, Subaru, Kit - Mishimoto Subaru WRX/STI cat-back exhausts allow your entire system to br
Takeda Takeda 49-36810-B: Takeda Exhaust Systems
Takeda 49-36810-B: Takeda 3 IN to 2-1/2 IN 304 Stainless Steel Cat-Back Exhaust w/ Black Tip Subaru WRX/STi 15-21 H4-2.0/2.5L (t) Takeda 49-36810-B fits these applications: 2015-2021 SUBARU WRX, 201
Takeda Takeda 49-36810-C: Takeda Exhaust Systems
Takeda 49-36810-C: Takeda 3 IN to 2-1/2 IN 304 Stainless Steel Cat-Back Exhaust Carbon Fiber Tip Subaru WRX/STi 15-21 H4-2.0/2.5L (t) Takeda 49-36810-C fits these applications: 2015-2021 SUBARU WRX,
Takeda Takeda 49-36810-L: Takeda Exhaust Systems
Takeda 49-36810-L: Takeda 3 IN to 2-1/2 IN 304 Stainless Steel Cat-Back Exhaust w/ Blue Flame Tip Subaru WRX/STi 15-21 H4-2.0/2.5L (t) Takeda 49-36810-L fits these applications: 2015-2021 SUBARU WRX
Takeda Takeda 49-36810-P: Takeda Exhaust Systems
Takeda 49-36810-P: Takeda 3 IN to 2-1/2 IN 304 Stainless Steel Cat-Back Exhaust w/ Polished Tip Subaru WRX/STi 15-21 H4-2.0/2.5L (t) Takeda 49-36810-P fits these applications: 2015-2021 SUBARU WRX,
Invidia Invidia N1 Exhaust
Throttle Body
Enlarged throttle bodies
Snow Performance Snow Performance 40076: Snow Performance Water-Methanol Injection Plates
Snow Performance 40076: 2004-2014 Subaru WRX STI Injection Plate - Snow Performance water-methanol injection plates are the easiest way to mount the Snow water-meth nozzles on your throttle body. Simp
Tune/ECU Flash
ECU tunes and flash calibrations
Cobb Cobb AccessPort Tune
Nitrous System
Wet and dry nitrous kits
Snow Performance Snow Performance 2110-BRD: Snow Performance Stage 2.5 Forced Induction Progressive Water/Methanol Injection Kits
Snow Performance 2110-BRD: Stage 2 Boost Cooler 2005-2014 Subaru WRX STI 2.5L Water-Methanol Injection Kit - Snow Performance stage 2.5 forced induction progressive water/methanol injection kits provi
Intercooler
Front mount and top mount intercoolers
Mishimoto Mishimoto MMTMIC-STI-08BKBK: Mishimoto Intercoolers
Mishimoto MMTMIC-STI-08BKBK: Intercooler Kit - Maximize your ride's performance with a Mishimoto intercooler! These high performance intercoolers significantly lower air intake temperatures, while saf
Mishimoto Mishimoto MMTMIC-STI-08BKBL: Mishimoto Intercoolers
Mishimoto MMTMIC-STI-08BKBL: Intercooler Kit - Maximize your ride's performance with a Mishimoto intercooler! These high performance intercoolers significantly lower air intake temperatures, while saf
Mishimoto Mishimoto MMTMIC-STI-08SLBK: Mishimoto Intercoolers
Mishimoto MMTMIC-STI-08SLBK: Intercooler Kit - Maximize your ride's performance with a Mishimoto intercooler! These high performance intercoolers significantly lower air intake temperatures, while saf
Mishimoto Mishimoto MMTMIC-STI-08SLBL: Mishimoto Intercoolers
Mishimoto MMTMIC-STI-08SLBL: Intercooler Kit - Maximize your ride's performance with a Mishimoto intercooler! These high performance intercoolers significantly lower air intake temperatures, while saf
Mishimoto Mishimoto TMIC
Downpipe
Catted and catless downpipes
Invidia Invidia Catless DP
Ready to build?
Use our interactive builder to pick your parts, see total HP gains, and simulate quarter-mile times.
Open the Builder