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IAG Stage 1 Head Package Stage 1 Cylinder Head Package w/ GSC S1 Cams W25 Casting

Engine Cylinder Head and Camshaft Kit


IAG Stage 1 Cylinder Head Package w/ GSC S1 Cams for 08-17 STI W25 Casting.

  • New Head Castings with Standard Sized GSC Valves, GSC Springs, Includes GSC S1 Cams
Pricing: $4,599.99

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


Subaru: WRX STI 13 - 21 Sport-tech / Tsurugi Edition / Launch Edition / Sport / Base / Limited / Series.HyperBlue / Kanrai Edition / STI / Type RA / S209, Subaru: WRX 12 - 16 STI, Subaru: Impreza 08 - 14 WRX STI Limited / WRX STI Special Edition / WRX STI

  • Final valve lash must be set after installation.
  • Recommendations / Warranty: Assembly and professional installation recommended. Workmanship/parts warranty will only be available for professionally installed cylinder heads.
  • Stage 1 Head Package Includes: (x2) Brand New Subaru OEM WRX STI Cylinder Head Castings, (x8) GSC 36mm (Standard) Intake Valves, (x8) GSC 32mm (Standard) Exhaust Valves, (x16) GSC Single Valve Springs & Titanium Retainers, (x16) OEM Valve Guides, (x16) GSC Valve Stem Seals, (x16) OEM Lifter Buckets, GSC S1 Billet Camshafts, Multi-Angle Valve Job, Machined Cam Lobe Clearance, Ultrasonic Cleaning, Bench Lashed, GSC V25, D25 and B25 Camshaft Specs: (04-07 STI / 06-14 WRX / 05-09 LGT / 04-13 FXT) S1 Billet Cam is intended for up to 500WHP 7025S1 ADV Duration Duration @ 0.040" Peak Lift Center Line Intake Exhaust, GSC W25 & N25 Camshaft Specs: (08-20 STI / 18-20 STI Type RA / 19 STI)S1 Billet Cam is intended for up to 500WHP 7026S1 ADV Duration Duration @ 0.040" Peak Lift Center Line Intake Exhaust

IAG Stage 1 Cylinder Head Package with GSC Stage 1 Cams: 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 W25 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 Billet S1 camshafts that are intended for vehicles making up to 500 wheel horsepower. During the final assembly, 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.


  • IAG-ENG-3015WS1
  • IAG-ENG-3015WS1
  • 887753779533
  • 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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