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IAG Performance Stage 3 Cylinder Head Package w/ GSC +1mm Valves and S2 Cams 2018-2019 STI Type RA N25 Heads

SKU IAG-ENG-3035NS2
Save $550.00 Save $550.00
Original price $5,499.99
Original price $5,499.99 - Original price $5,499.99
Original price $5,499.99
Current price $4,949.99
$4,949.99 - $4,949.99
Current price $4,949.99

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 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. 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 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 Billet S2 camshafts intended for vehicles making 500-700 wheel horsepower. The cams are matched to GSC Single Valve Springs and Titanium Retainers along with GSC Viton stem seals then bench-lashed to a tolerance that is close to final specifications.


Stage 3 Ported Head Package Includes:

  • (x2) Brand New Subaru OEM 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
  • (x16) OEM Lifter Buckets
  • GSC S2 Billet Camshafts
  • IAG Performance CNC Pocket Porting
  • Multi-Angle Valve Job
  • Machined Cam Lobe Clearance
  • Resurface
  • Ultrasonic Cleaning
  • Bench Lashed


GSC N25 and W25 Camshaft Specs: (08-20 STI / 18-20 STI Type RA / 19 STI)
S2 Billet Cam is intended for 500-700WHP

7026S2 ADV Duration Duration @ 0.040" Peak Lift Center Line
Intake 272° 233° 10.80mm 125°
Exhaust 272° 233° 10.50mm 128°



Recommendations / Warranty:

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

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