Cobb Fuel Rail/ Line Kit – 2008-2021 Subaru STI

Cobb Fuel Rail / Line Kit — 2008-2021 Subaru STI

The Cobb Fuel Rail and Line Kit for the 2008-2021 Subaru STI upgrades the factory fuel rail and delivery lines with components sized for the fuel flow demands of high-power EJ257 builds.

DETAILS

• Platform: 2008-2021 Subaru WRX STI EJ257
• Improved fuel rail and delivery line routing for high-power builds
• Correctly sized for high injector flow rate demand
• All hardware and fittings included
• ProTuner custom calibration required for high-power builds

Fuel Rail and Line Design 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.

Compatibility with FPR and Injector Upgrades

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 rail
• Cobb fuel lines
• 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 rail and line kit for the 2008-2021 STI is the fuel routing component of a comprehensive fuel system upgrade. Used with the Cobb fuel pressure regulator and high-flow fuel pump for a complete high-power fuel system.

Fitment

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