Radium Engineering FPR RA Fuel Pressure Regulator Kit for Subaru STI 2008-2021

Radium FPR RA Fuel Pressure Regulator Kit - Subaru STI 08-21

Application: Subaru WRX STI (2008-2021) – EJ257
Part Type: Fuel pressure regulator kit with RA-series multi-port regulator
Part Number: 20-0965

The Radium FPR Kit replaces the OEM fuel pressure regulator and damper assembly on the 2008-2021 Subaru WRX STI. The factory STI layout is a quasi dead-end system – this kit reroutes fuel through the fuel rails first, then through the regulator and back to the tank, the arrangement Subaru tuners prefer for curing stumbling issues. The vacuum reference is also rerouted from the #4 cylinder runner to the intake plenum for a steadier signal.

The RA-series regulator installs in the OEM regulator location and features tool-less pressure adjustment, a single stainless steel return orifice for laminar flow and a 360° swivelling, double O-ring sealed vacuum port.

Key Features

• Return-Style Routing: Fuel passes through the rails before the regulator and returns to the tank
• Improved Vacuum Reference: Rerouted from the #4 cylinder runner to the intake plenum for a steadier signal
• OEM Location: Regulator installs where the factory regulator was mounted
• Stable Pressure: Single stainless steel return orifice designed for laminar flow
• Tool-less Adjustment: Turn the knob to set fuel pressure – detents give approx. 1 psi (±0.5 psi) per click, no jam nut or set screw
• Swivel Vacuum Port: 360° swivelling, double O-ring sealed vacuum reference port
• Interchangeable Vacuum Fittings: Four 10-32 threaded fittings: 5mm barb, 3AN male, push-to-connect and vacuum plug
• Fuel Compatibility: All petrol types (unleaded, leaded, oxygenated, pre-mix) plus methanol, ethanol and E85

What's Included

• RA-series multi-port fuel pressure regulator
• OE fuel line disconnect tool
• SAE quick connect to AN adapters
• EFI hose and PushLok hose ends
• Vacuum hose
• All necessary fittings and installation hardware

Optional Parts

• Radium Fuel Pressure Gauge w/8AN ORB Adapter (20-0386) – Installs in the unused 8AN ORB port on the regulator for setting and monitoring fuel pressure

Important Notes

• Radium lists fitment for the USDM 2008-2021 WRX STI with the EJ257 engine only – contact us to confirm fitment for your vehicle
• Fuel pressure gauge is sold separately
• A rapid fuel pressure drop after shut-off is normal for aftermarket regulators – pressure resets when the pump runs again
• Long cranking or slow pressure build-up is not caused by the regulator – it typically indicates fuel draining back to the tank from an internal pump module leak (e.g. venturi jet pump or missing check valve)
• Installation instructions are available in the Instructions tab

Vehicle Fitment

• Subaru WRX STI (2008-2021) – EJ257 engine only

If you're unsure whether this will fit your vehicle, contact our team of experts via email at hello@iilumolab.com and send through a few photos of the car for us to verify fitment.

Installation

We always recommend professional fitment for guaranteed satisfaction. If you're wanting a hassle-free installation, feel free to contact our friendly team as we offer installation services in-store at our Melbourne workshop. For more details, contact us here.

Note

Upon receiving the item, please ensure that the part is indeed the correct item you have ordered. This can be achieved by checking labels on the packaging. Please also ensure a proper test fit of the item is conducted prior to paint and/or installation. Returns/Warranty claims will be voided if the item has been tampered with, or is no longer in resalable/new condition.