Cobb Fuel System Package – 2008-2021 Subaru STI

Cobb Fuel System Package — 2008-2021 Subaru STI

The Cobb Fuel System Package for the 2008-2021 Subaru STI bundles the fuel rail and fuel line kit with the fuel pressure regulator kit — the complete fuel system upgrade for high-power STI builds needing improved fuel delivery consistency and pressure regulation beyond the factory system’s capability.

DETAILS

• Platform: 2008-2021 Subaru WRX STI EJ257
• Includes: Cobb fuel rail / line kit + Cobb fuel pressure regulator kit
• Fuel rail and lines: improved fuel routing for high-demand builds
• Fuel pressure regulator: maintains correct rail pressure at high flow rates
• For high-power builds requiring consistent fuel delivery above factory capability
• ProTuner custom calibration required when used with larger injectors

Complete Fuel Delivery: Rail, Lines, and Pressure Regulation

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.

High-Power EJ257 Builds and ProTuner Integration

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 and line kit
• Cobb fuel pressure regulator kit
• 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 System Package for the 2008-2021 STI is the complete fuel delivery upgrade for EJ257 builds making serious power. The factory fuel rail, lines, and regulator are adequate for stock and mild builds but become limiting factors as power increases through upgraded turbochargers, larger injectors, and flex fuel. The package bundles the two key hardware pieces into a single purchase.

Fitment

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