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IAG Stage 5 CNC Ported Heads Pkg Stage 5 CNC Ported Heads w/CM w/ +1mm Ferrea Valves & GSC S3 CamsS20 Casting

Engine Cylinder Head and Camshaft Kit


IAG Stage 5 CNC Ported Chamber Matched Heads w/ +1mm Ferrea Valves & GSC S3 Cams for 02-05 WRX S20 Casting.

  • New Head Castings, Fully CNC Ported with +1mm Ferrea Valves, Ferrea Drag Springs, GSC S3 Cams
Pricing: $7,679.99

Free ground shipping on all order over $100.00 (some exclusions may apply)


Saab: 9-2X 05 - 05 Aero, Subaru: Impreza 02 - 05 WRX

  • Recommendations / Warranty: Assembly and professional installation recommended. Workmanship/parts warranty will only be available for professionally installed cylinder heads.
  • Stage 5 Ported Head Package Includes: (x2) Brand New Subaru OEM S20 Cylinder Head Castings, (x8) Ferrea 37mm (+1mm) Comp Plus Intake Valves, (x8) Ferrea 33mm (+1mm) Comp Plus Exhaust Valves, (x16) Ferrea Dual Valve Springs & Titanium Retainers, (x16) GSC Copper / Bronze Valve Guides, (x8) Ferrea 6mm Intake Valve Stem Seals, (x8) Ferrea 6mm Exhaust Valve Stem Seals, (x1) GSC S3 Billet Camshaft Set, (x16) OEM valve lifters, IAG Performance CNC Porting, CNC Chamber Modification, Multi-Angle Valve Job, Drilling for compatibility with 1/2" or 14mm Head Studs, Cam Clearancing, Ultrasonic Cleaning

IAG's Stage 5 Cylinder Head Package utilizes a CNC porting program for the S20 heads that was developed over the past five years and tested on the most successful high-horsepower Subarus. The ported head package starts with brand new S20 OEM WRX head castings directly from Subaru. The bare castings are inspected then fixtured into our state of the art Centroid 5-axis CNC Machine. The Centroid CNC ports the intake and hard to reach exhaust "dog-leg" port runner. CNC porting is not only an efficient way of machining the heads it also offers consistent port results every time. Next, the heads receive our combustion chamber modification in which the shape of the chambers are machined to match those of an STI head. Once the Centroid completes this process the heads undergo a cam clearance process to remove material from the lifter area where large duration cam profiles are known to contact the castings. The heads are then drilled to fit larger 1/2" or 14mm head studs for maximum clamping force. Next, the OEM guides are removed and replaced in favor of Ferrea Copper / Bronze valve guides that offer greater heat dissipation, lubricity properties and are shaped to improve flow. Once all the new intake and exhaust guides are in place they are diamond-honed in our honing station. Next our Serdi 3.0 Valve Guide and Seat Machine cuts all intake and exhaust seats with multi-angle valve job that suits the flow characteristics of Ferrea Comp Plus +1mm valves. At this point, the heads decks are resurfaced using our TS-3000 BlockMate that cuts the aluminum to a smooth even finish. Next, the heads are ultrasonically cleaned to remove debris and oils from the machining process. The heads are then reassembled using GSC Billet S3 camshafts designed for drag racing applications intending to make 700+ wheel horsepower. The cams are matched to Ferrea Dual Valve Springs and Titanium Retainers along with Ferrea valve stem seals then bench-lashed to a tolerance that is close to final spec.


  • IAG-ENG-3055SCS3
  • IAG-ENG-3055SCS3
  • 887753780973
  • IAG Performance
  • New


Shipping Information

  • Item Requires Shipping
  • 92.0 lbs.
  • W16.0000” x H12.0000” x L20.0000”
  • Free ground shipping on all order over $100.00 (some exclusions may apply)

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