Radium Engineering RA-Series FPR Kit – Subaru STI 2008–2021

The Radium Engineering Fuel Pressure Regulator Kit is designed as a direct replacement for the OEM regulator found on the USDM 2008–2021 Subaru WRX STi (EJ257 only). This bolt-in solution relocates the regulator to a more efficient position after the fuel rails, resolving the common stumbling and hesitation issues experienced with the OEM dead-end style system.

The Radium kit re-routes fuel to circulate through both fuel rails before reaching the regulator and returning to the tank, as preferred by experienced Subaru tuners. It mounts in the OEM location and includes fittings and vacuum hose to relocate the vacuum reference source to the intake manifold plenum for a stable signal.

Features:

• Replaces OEM fuel pressure regulator and damper assembly

• Re-routes fuel through both rails before returning to the tank

• Mounts in OEM location with supplied bracket

• Vacuum reference relocation hardware included

• RA-series regulator features tool-less pressure adjustment with incremental detents

• 360-degree swiveling vacuum reference port for easy routing

• Suitable for high horsepower applications and all fuel types including E85

RA-Series Regulator Features:

• Tool-less pressure adjustment with a simple turn of the knob

• Incremental detents provide haptic feedback for 1psi (+/- 0.5psi) adjustment

• 360-degree swiveling vacuum reference port with double O-ring seal

• Single stainless steel return orifice for smooth laminar flow

Vacuum Port Fitting Options:

• Barbed Fitting: Black zinc-plated 5mm barb compatible with 4mm, 5mm, and 6mm vacuum hoses

• 3AN Male Fitting: Black zinc-plated steel, compatible with 3AN hose ends

• Push-To-Connect: Nickel-plated brass, fits hard plastic 6.35mm OD tubing

• Vacuum Plug: Black oxide stainless steel screw to maintain constant pressure

Fuel Compatibility:
This regulator kit is fully compatible with all fuel types including unleaded, leaded, oxygenated, pre-mixed, ethanol, methanol, and E85.