IAG Side Feed to Top Feed Fuel Rail Conversion Kit — Black — 2004-2006 Subaru STI
Top-Feed Conversion for Side-Feed STI Applications
The IAG Side Feed to Top Feed Fuel Rail Conversion Kit enables a top-feed injector conversion on 2004-2006 STI models that use factory side-feed injectors — without requiring a switch to top-feed TGVs. Using IAG’s billet aluminum rails and conversion bosses, this kit allows larger, higher-flow top-feed injectors to be used in the existing side-feed manifold architecture, raising the fuel delivery ceiling to 350 BHP and beyond. Real-world tested to 850 horsepower. Black anodized finish.
DETAILS
- Color: Black anodized finish with IAG engraved logo
- Enables top-feed injector use with factory side-feed TGVs
- Machined from solid 6061 billet aluminum
- 5/8″ I.D. bore — accepts -8 O-ring boss fittings
- Parallel flow format for even fuel distribution
- Real-world tested to 850 horsepower
- Allows fuel delivery beyond 350 BHP
- Tested with Injector Dynamics 1050X, 1300X, and 1700X injectors
- NOT compatible with ID2000cc injectors without switching to a different top hat
- Injector tension springs (IAG-AFD-2129) available separately for older ID2000 injectors
- Does not include fuel lines
- Package includes: (2) billet top-feed fuel rails, (4) side-feed to top-feed injector conversion bosses, (4) bolts, (4) phenolic spacers, (4) injector O-rings
- Fits: 2004-2006 Subaru STI (side-feed injector models)
Why a Conversion Kit vs Standard Top-Feed Rails
Standard top-feed rail conversions require switching from OEM side-feed TGVs to top-feed TGVs, which adds significant cost and installation complexity. IAG’s conversion kit uses machined bosses to adapt top-feed injectors to the existing side-feed manifold architecture, eliminating the need for TGV replacement. This makes a top-feed conversion practical and cost-effective on 2004-2006 STI models.
Injector Compatibility
The kit is tested and confirmed to work with Injector Dynamics 1050X, 1300X, and 1700X injectors. It is NOT compatible with ID2000cc injectors without substituting a different billet top hat (available separately). For builders using older-generation ID2000 injectors, the IAG-AFD-2129 tension spring kit is available separately.
Parallel Flow Design
Like IAG’s standard V3 rails, this conversion kit uses a parallel flow format to deliver equal fuel pressure to each injector. Each cylinder bank receives the same fuel pressure with matched flow between rails — critical for even fueling at high power levels.
Why Choose IAG Performance
IAG Performance has been building Subaru-specific engine and drivetrain components since 2001, and in that time they have become the standard by which serious Subaru builds are measured. Based in Westminster, Maryland, IAG designs, machines, and assembles their products in-house using Haas CNC equipment and their own engineering team. Their catalog spans everything from short blocks and long blocks rated to 1150 BHP all the way down to the fuel system, oiling, and drivetrain hardware that keeps modified Subarus running reliably for years. Every IAG product exists because a problem needed a better solution than what was available — and the engineering shows.
The RallySport Take
The IAG Side Feed to Top Feed conversion is the most practical way to access high-flow injectors on a 2004-2006 STI without replacing the TGVs. Real-world tested to 850 horsepower, this kit has been proven in serious builds. If you are building a high-power 04-06 STI and need more fuel delivery, this is how you get there without replacing the entire intake manifold system.
Fitment
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2004-2006 | Subaru | Impreza | STI |
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