Quick answer

Choose 750cc injectors for moderate power goals on 2002-2014 WRX/STI and 2007-2012 Legacy GT, or 2200cc injectors for high-horsepower builds on 2004-2006 STI and Legacy GT models that need a side-feed to top-feed conversion.

What the injector size means for your build

Injector flow rating (cc/min at a given pressure) directly determines how much fuel your engine can deliver. A 750cc injector set supports roughly 400-500 whp on a typical Subaru, while 2200cc injectors can handle 700+ whp. The right choice depends on your turbo, fuel system, and power target—not just the biggest number.

Conversion vs. upgrade rails: the fit difference

DeatschWerks offers two distinct families: conversion fuel rails that change a side-feed manifold to top-feed (for 2004-2006 STI and Legacy GT), and upgrade fuel rails that replace the stock top-feed rails on 2002-2014 WRX, 2007-2015 STI, and 2007-2012 Legacy GT. If you own a 2004-2006 STI and want 2200cc injectors, you must use the conversion kit. For later models or smaller injectors, the upgrade kit is simpler and costs less.

Decision rules: 750cc vs 2200cc

  • Power target under 500 whp: Choose the upgrade fuel rails with 750cc injectors. They provide ample headroom, bolt directly to top-feed manifolds, and cost significantly less.
  • Power target over 500 whp or future-proofing: Choose the 2200cc injector kits. For 2004-2006 STI/Legacy GT, select the conversion fuel rails; for later models, the upgrade fuel rails with 2200cc injectors work. Verify your manifold type (side-feed vs top-feed) before ordering.
  • Model year and manifold type: 2004-2006 STI and Legacy GT use side-feed fuel rails. You must use the conversion kit to switch to top-feed for 2200cc injectors. All other supported models already have top-feed and can use upgrade rails. Check your vehicle’s year and manifold type; the conversion kit is required for early STI models with 2200cc injectors.

Product facts at a glance

  • Subaru conversion fuel rails and 2200cc injectors: Subaru conversion fuel rails and 2200cc injectors; fits 2004-2006 STI and Legacy GT; converts side feed to top feed. This is the only way to run 2200cc injectors on early STI models that have a side-feed manifold.

    Subaru conversion fuel rails and 2200cc injectors

    Subaru conversion fuel rails and 2200cc injectors

  • Subaru upgrade fuel rails and 750cc injectors: Subaru upgrade fuel rails and 750cc injectors; fits MPFI WRX 2002-2014, STI 2007-2015, Legacy GT 2007-2012. Offers a cost-effective, drop-in upgrade for moderate power targets without changing the manifold type.

    Subaru upgrade fuel rails and 750cc injectors

    Subaru upgrade fuel rails and 750cc injectors

Which kit fits your build?

Best for

  • Moderate-power Subaru builds (400-500 whp) on 2002-2014 WRX, 2007-2015 STI, or 2007-2012 Legacy GT
  • High-horsepower builds (700+ whp) on 2004-2006 STI or Legacy GT needing a side-feed conversion

Not for

  • 2004-2006 STI owners who want 750cc injectors (conversion kit not available for that size; use upgrade rails on later models)
  • Builds with a stock fuel system that cannot supply enough volume for 2200cc injectors