Time was, you could just plop parts on your car, and everything would be fine.  These days even a simple intake can wreak havoc with your car's sensitive air/fuel metering, and modifying without proper ECU tuning can be disastrous. Look to Mach V Motorsports to set you up with the proper ECU tuning solutions for your Subaru.

Here you'll find the supremely powerful Cobb AccessPort ECU tuning systems for all turbo Subaru cars (including WRX, WRX STI, Legacy GT/Outback XT, and Forester XT), 3-port boost control solenoids, and stand-alone boost controllers for managing manifold pressure.