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,…
The IAG 750 sits in a specific part of the EJ25 build spectrum. It is not the entry point into closed-deck territory. It is also not a competition engine. Instead, it is…
Head gasket failure is one of the most common and most expensive outcomes of pushing an EJ-series Subaru beyond its stock limits. In most cases, the failure is not a head gasket…
Wheel studs are not a glamorous upgrade. They do not add horsepower or improve lap times on their own. However, for any Subaru WRX or Subaru STI owner running a wheel and…
The EJ257 in the Subaru STI is a capable engine, but its open-deck architecture has a well-documented ceiling. As boost increases and tuning becomes more aggressive, cylinder wall distortion, head gasket failure,…
The stock Subaru STI turbocharger handles daily driving well, but it runs out of headroom well before most build goals. If the target is 450 to 500 horsepower on an EJ25, the…
The COBB Accessport faceplate is one of the most commonly asked-about COBB accessories for the WRX and STI. Simple to understand, takes seconds to install, and makes a visible difference on a…
The IAG 1150 sits at the top of the IAG closed deck short block lineup. Most owners research it. Fewer actually need it. IAG builds it for extreme power applications where the…
The IAG 950 is the most popular closed deck short block for serious WRX and STI builds. Not because it is the most powerful IAG option, but because it fits the majority…
Clutch Masters is one of the most respected clutch brands in performance driving and one that WRX and STI owners frequently ask about when they outgrow the stock clutch. The FX350 and…
The EJ257 in the STI is one of the most capable engines fitted to a production performance car. It is also one of the most commonly damaged when pushed past its limits…