To improve a Subaru WRX’s handling and performance, some parts may need to be physically changed, installed, or removed. The installation of an upgraded intake or a cold air intake are some of the more popular mechanical upgrades made to the Subaru WRX.
A Subaru WRX can also be electronically tuned without ever having its physical characteristics changed. This is achieved by remapping engine characteristics via the engine control unit or with an OBD-II scanner—with this method, the driver can modify power output, fuel efficiency, etc.