IAG Stage 1 Cylinder Head Package

2019Subaru STi Stage 1 Cylinder Head Package by IAG Performance

IAG’s Stage 1 cylinder heads are intended for those looking for a cost-effective OEM+ replacement. Each package starts with brand new WRX STI OEM head castings, directly from Subaru of America.

The bare castings are visually inspected and then fixtured into our in-house Centroid 5-axis CNC Machine. This is one of the most advanced pieces of precision engine machining equipment in the world. In the Centroid, the heads undergo a cam clearance machining process which removes material from the lifter area where larger lift and duration cam profiles are known to contact the castings.

Then the heads are then fixtured in our Serdi 3.0 Valve Guide and Seat Machine to cut all intake and exhaust seats with a multi-angle valve job that suits the flow characteristics of GSC’s standard size 36mm Intake and 32mm Exhaust valves.

At this point, the heads’ decks are resurfaced using our TS-3000 BlockMate, which cuts the aluminum to a smooth, even finish. Next, the heads are ultrasonically cleaned to remove debris and oils from the machining process.

Finally, the heads are reassembled using GSC Single Valve Springs and Titanium Retainers along with GSC Viton stem seals. If you prefer, the heads can be assembled using GSC Billet S1 camshafts that are intended for vehicles making up to 500 wheel horspower.

Features

• Brand New Subaru OEM WRX STI Cylinder Head Castings
• GSC 36mm (Standard) Intake Valves
• GSC 32mm (Standard) Exhaust Valves
• GSC Single Valve Springs & Titanium Retainers
• OEM Valve Guides
• GSC Valve Stem Seals
• Multi-Angle Valve Job
• Machined Cam Lobe Clearance
• Resurface
• Ultrasonic Cleaning
• Option to include GSC Billet S1 Cams (rated up to 500whp)

Please Note: Assembly and professional installation recommended. Workmanship/parts warranty will only be available for professionally installed cylinder heads.

Applications

• 2019Subaru STi
• 2018 – 2019 Subaru STi Type RA

Specifications (GSC S1 In. Cams)

• ADV Duration: 264
• Duration @ 0.040″: 226
• Peak Lift: 10.80mm
• Center Line: 125

Specifications (GSC S1 Ex. Cams)

• ADV Duration: 264
• Duration @ 0.040″: 222
• Peak Lift: 10.50mm
• Center Line: 128

What’s In The Box?

• 2 – OEM Cylinder Head Castings
• 8 – GSC 36mm Intake Valves
• 8 – GSC 32mm Exhaust Valves
• 16 – GSC Single Valve Springs & Titanium Retainers
• 16 – OEM Valve Guides
• 16 – GSC Valve Stem Seals
• GSC S1 Billet Cams (OPTIONAL)
• OEM Lifter Buckets (OPTIONAL)

Warranty

• Manufacturer Standard Warranty. Workmanship/parts warranty will only be available for professionally installed cylinder heads.