PERRIN 15-21 Subaru WRX & STI / 12-25 Impreza / 24-25 Crosstrek Differential Lockdown System

A big brake kit doesn't shorten your stopping distance — tires do. What it actually buys is heat capacity and pedal consistency. How to choose rotor diameter, piston area and pad compound, and when fluid and pads are the smarter spend.

Almost every cat-back horsepower claim online is unsourced. Here's what an independent dyno test actually measured, why scavenging lives in the headers and not the cat-back, and where the power really is on a turbo car.

Both lower the car — but the decision is really about the damper. Why stock dampers and aftermarket spring rates fight each other, when springs are genuinely the right call, and what each path costs you beyond the parts.