More boost sounds simple on paper. Push the number up, make more power, done. Reality works differently. Every EJ or FA engine has a point where cylinder pressure outpaces what the internals,…
The EJ257 and FA24 are the two turbocharged Subaru engines most WRX and STI owners encounter when researching builds or considering a platform change. The EJ257 powers the Subaru STI through its…
The Subaru STI is one of the most capable performance cars available at its price point, but the EJ257 engine that powers it has well-documented limits under sustained high boost. Understanding where…
The factory turbocharger on the Subaru STI is a capable unit for stock and mildly modified builds, but it has a ceiling. As boost targets increase and power goals climb past what…
The EJ207 and EJ257 are both flat-four turbocharged engines from Subaru’s EJ engine family, and both power versions of the Subaru STI. However, they are not the same engine, and the differences…
Most Subaru WRX and Subaru STI builds run internal wastegates from the factory. The stock turbo manages boost pressure through an integrated valve inside the turbine housing, which works adequately at factory…
The 2015 to 2021 Subaru WRX runs a plastic end tank radiator from the factory. Under normal driving conditions it keeps coolant temperatures within range, but its thermal capacity becomes a limiting…
Choosing the right brake pad for a Subaru WRX depends on how the car is used. A daily driver that occasionally sees spirited roads has different needs than a car that runs…
The stock brake rotors on the 2015 to 2021 Subaru WRX are adequate for normal driving conditions, but they show their limits quickly under harder use. Repeated heavy braking generates heat the…
The ACT HD Street Sprung Clutch Kit covers a large portion of STI builds well, but it has a ceiling. For owners running higher torque, larger turbos, or planning track sessions where…
The factory downpipe on the 2015 and newer Subaru WRX is one of the more restrictive points in the exhaust system. Because it sits directly after the turbo, restriction here has an…
Coolant temperature is one of the quieter limiting factors on a modified Subaru WRX or Subaru STI. The factory radiator works adequately for stock power levels, but as boost increases, ambient temperatures…
The factory EJ25 has a well-documented ceiling. Under sustained high boost, the stock pistons crack, the connecting rods bend, and ringland failure becomes a matter of when rather than if. For Subaru…
Most WRX and STI fuel pump upgrades start and end with a drop-in replacement. The pump slots into the factory basket, the wiring connects to the stock harness, and the job is…
The stock Subaru STI clutch handles daily driving well, but it has a torque ceiling. As boost increases and power climbs, the factory clutch begins to slip under load, engagement becomes inconsistent,…