COBB Tuning Fuel Rails – 2008-2021 Subaru STI

Cobb Fuel Rails — 2008-2021 Subaru STI

The Cobb Fuel Rails for the 2008-2021 Subaru STI are upgraded fuel rails providing improved fuel distribution across all four injectors for high-flow EJ257 builds. Larger internal volume than factory rails reduces the pressure drop between the regulator and individual injectors under high demand.

DETAILS

• Platform: 2008-2021 Subaru WRX STI EJ257
• Upgraded fuel rails — larger internal volume than factory
• More consistent fuel pressure distribution across all four injectors
• For high-flow EJ257 builds with upgraded injectors
• All hardware and fittings included

Larger Volume Fuel Rails for High-Flow EJ257 Builds

A fuel pressure regulator maintains a constant fuel rail pressure relative to intake manifold pressure. Stock fuel pressure regulators on most Subaru STI applications maintain adequate fuel pressure for factory power levels, but as power increases through larger turbochargers, higher boost, and higher injector duty cycles, the factory regulator can become a limiting factor. An upgraded fuel pressure regulator provides consistent rail pressure at higher flow rates — ensuring the injectors receive the correct pressure differential regardless of how hard the fuel system is being pushed.

Consistent Pressure Distribution and Injector Compatibility

The Cobb fuel pressure regulator installs at the factory location on the fuel rail, using the factory fuel line connections. Fuel pressure is adjustable on some variants via a bleed screw, allowing the base pressure to be dialed in to match the injector and fuel pump combination in the build. A fuel pressure sensor kit is typically used alongside the regulator to monitor actual rail pressure in real time via the Accessport gauge display — providing confirmation that the regulator is maintaining correct pressure during hard acceleration.

What’s in the Box

• Cobb fuel rails (pair)
• All hardware and fittings

Why Choose Cobb Tuning

Cobb Tuning has been developing performance software and hardware for turbocharged enthusiast vehicles since 1999. Founded in Austin, Texas, Cobb built its reputation on the Accessport and expanded into a full catalog of hardware engineered to complement it. Every OTS map is developed in-house on real vehicles, and every hardware product is validated as part of a complete system — not sourced and sold in isolation. That integrated approach is why Cobb produces consistent, reliable results across the builds we see every day.

The RallySport Take

The Cobb fuel rails for the 2008-2021 STI are the fuel distribution hardware for high-flow EJ257 builds. The larger internal volume provides more consistent pressure distribution between injectors, reducing the injector-to-injector variation that factory rails can produce at high flow rates.

Fitment

Year	Make	Model	Notes
2008-2021	Subaru	WRX STI	EJ257 MT