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IAG Performance Stage 3 Cylinder Head Package w/ +1mm GSC Valves 2002-2005 WRX 2.0L S20 Heads

Original price $3,629.99 - Original price $3,629.99
Original price
$3,629.99 - $3,629.99
Current price $3,629.99

The head package centers around our popular CNC pocket porting program which was developed over the last several years. Pocket porting removes excess OEM casting flash and the material underneath the valves. By smoothing and blending this area under the valve seat, significant flow capability can be achieved.

The IAG Stage 3 pocket ported head package starts with brand new S20 2002-05 WRX 2.0L OEM head castings, directly from Subaru of America. The bare castings are visually inspected then fixtured into our in-house Centroid 5-axis CNC Machine, one of the most advanced precision engine machining equipment in the world. The Centroid CNC ports the intake and exhaust runners under the valves and blends them to the valve seat. Once the Centroid completes the port process the heads receive our (optional) combustion chamber modification in which the shapes of the chamber are machined to reduce compression and improve the burn path. The heads then 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. Next, 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 +1mm valves. At this point, the heads decks are resurfaced using our TS-3000 BlockMate that cuts the aluminum to a smooth even finish. Then, 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.

Stage 3 Ported Head Package Includes:

  • (x2) Brand New Subaru OEM S20 Cylinder Head Castings
  • (x8) GSC 37mm (+1mm) Intake Valves
  • (x8) GSC 33mm (+1mm) SuperAlloy Exhaust Valves
  • (x16) GSC Single Valve Springs & Titanium Retainers
  • (x16) OEM Valve Guides
  • (x16) GSC Valve Stem Seals
  • IAG Performance CNC Pocket Porting
  • Multi-Angle Valve Job
  • Machined Cam Lobe Clearance
  • Resurface
  • Ultrasonic Cleaning

Recommendations / Warranty:

  • For use with stock cams or mild duration cams
  • Assembly and professional installation recommended.
  • Workmanship/parts warranty will only be available for professionally installed cylinder heads.

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