Radium Engineering 08-21 Subaru WRX STi (EJ257 Only) RA-Series Fuel Pressure Regulator Kit

For a properly planned performance build, the Radium Engineering 08-21 Subaru WRX STi (EJ257 Only) RA-Series Fuel Pressure Regulator Kit controls EFI fuel pressure and returns excess fuel so injectors see a stable, tunable pressure supply. Radium regulators are intended for performance return-style systems where consistent pressure control is important as fuel demand and manifold pressure change.

Fitment is specific to 08-21 Subaru WRX STi (EJ257 Only) RA-Series; confirm the vehicle and surrounding hardware before ordering. A fuel return must be routed back to the tank or surge tank. Match regulator port sizes and pressure range to the fuel-system design.