Fuel Regulators

Fuel Regulators: hold your rail pressure steady under boost and load

A fuel pressure regulator sets the pressure your injectors see. It bleeds excess fuel back toward the tank so the rail stays at a controlled value instead of climbing with pump output or dropping as demand spikes. On a stock setup that keeps the mixture predictable; on a tuned or higher-flow build it's what stops fuel delivery from wandering when you add a bigger pump or more boost. Getting the right regulator is a normal step whenever you change fueling, and the fuel regulators here are aimed at exactly that job. It's a part you fit once, plumb correctly, and forget.

What's stocked here

There are 8 fuel regulators in stock right now, across 3 brands: COBB, Radium Engineering and TwinPower. Current pricing runs from $45 to $430, which is the live range for what's on the shelf, not a standing promise. COBB makes up the largest share of the sample with four listings, Radium Engineering has three, and TwinPower one.

Concrete examples span that spread. At the top, the COBB 08-21 Subaru STI Fuel Pressure Regulator Kit and the rail-specific COBB STI regulator for the fuel rail kit are platform-focused parts. The Radium Dual Fuel Pressure Regulator (DFPR) and the Radium Multi-Port Regulator (MPR) in green are the standalone, plumb-it-yourself options. At the low end, the TwinPower 95-01 FLH/FLT regulator is a motorcycle replacement unit.

How to choose

The split here is between a bolt-on kit for a specific vehicle and a universal regulator you plumb into your own fuel system. The COBB Subaru parts are built around the STI platform, so if that's your car they take the guesswork out of ports and mounting. The Radium DFPR and MPR are the flexible route: more work to plumb, but they suit a custom rail or fuel setup where you control the routing. The TwinPower unit is a straight replacement for the Harley FLH/FLT application it lists. Match the part to how much of your fuel system you're actually building versus replacing.

What else you need with it

A regulator rarely goes in alone. If you're touching fuel delivery, look at Fuel Pumps at the same time so pump and regulator are sized together. Plumbing it means Fittings and Adapters to land the ports and lines cleanly. If the engine is open for other work, the Gasket Kits section is worth a look. All of these sit under the wider Engine Components section.

Fitment and ordering

Fitment data is listed on 4 of these parts, covering Subaru and Harley-Davidson across model years 1995 to 2023, including the Subaru WRX STI, WRX, and Harley-Davidson FLH and FLT. Confirm your exact application before ordering. If you're unsure, call fitment help at 813-535-5801 or use the contact page, and check the FAQ for common questions. All orders ship free, and Affirm and Katapult financing is available at checkout.

Fuel Regulators: hold your rail pressure steady under boost and load

A fuel pressure regulator sets the pressure your injectors see. It bleeds excess fuel back toward the tank so the rail stays at a controlled value instead of climbing with pump output or dropping as demand spikes. On a stock setup that keeps the mixture predictable; on a tuned or higher-flow build it's what stops fuel delivery from wandering when you add a bigger pump or more boost. Getting the right regulator is a normal step whenever you change fueling, and the fuel regulators here are aimed at exactly that job. It's a part you fit once, plumb correctly, and forget.

What's stocked here

There are 8 fuel regulators in stock right now, across 3 brands: COBB, Radium Engineering and TwinPower. Current pricing runs from $45 to $430, which is the live range for what's on the shelf, not a standing promise. COBB makes up the largest share of the sample with four listings, Radium Engineering has three, and TwinPower one.

Concrete examples span that spread. At the top, the COBB 08-21 Subaru STI Fuel Pressure Regulator Kit and the rail-specific COBB STI regulator for the fuel rail kit are platform-focused parts. The Radium Dual Fuel Pressure Regulator (DFPR) and the Radium Multi-Port Regulator (MPR) in green are the standalone, plumb-it-yourself options. At the low end, the TwinPower 95-01 FLH/FLT regulator is a motorcycle replacement unit.

How to choose

The split here is between a bolt-on kit for a specific vehicle and a universal regulator you plumb into your own fuel system. The COBB Subaru parts are built around the STI platform, so if that's your car they take the guesswork out of ports and mounting. The Radium DFPR and MPR are the flexible route: more work to plumb, but they suit a custom rail or fuel setup where you control the routing. The TwinPower unit is a straight replacement for the Harley FLH/FLT application it lists. Match the part to how much of your fuel system you're actually building versus replacing.

What else you need with it

A regulator rarely goes in alone. If you're touching fuel delivery, look at Fuel Pumps at the same time so pump and regulator are sized together. Plumbing it means Fittings and Adapters to land the ports and lines cleanly. If the engine is open for other work, the Gasket Kits section is worth a look. All of these sit under the wider Engine Components section.

Fitment and ordering

Fitment data is listed on 4 of these parts, covering Subaru and Harley-Davidson across model years 1995 to 2023, including the Subaru WRX STI, WRX, and Harley-Davidson FLH and FLT. Confirm your exact application before ordering. If you're unsure, call fitment help at 813-535-5801 or use the contact page, and check the FAQ for common questions. All orders ship free, and Affirm and Katapult financing is available at checkout.