IAG Performance IAG-ENG-3045WS3 Stage 4 CNC Ported Heads w/ +1mm GSC Valves & GSC S3 Camshafts W25 Casting

IAG Stage 4 Ported Heads with +1mm GSC Valves & Cams: IAG's Stage 4 Cylinder Head Package utilizes a CNC porting program for the WRX STI 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 WRX STI OEM W25 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 hard to reach exhaust "dog-leg" port runner. CNC porting offers consistent port results every time. Once the Centroid completes the port process the heads undergo a cam clearance machining process that removes material from the lifter area where large duration cam profiles are known to contact the castings. Short after the heads are drilled to fit larger 1/2" or 14mm head studs which are commonly used in high horsepower builds. Next, the OEM guides are pressed out and replaced in favor of GSC Manganese-Bronze valve guides that are shaped to improve airflow. Once all the new intake and exhaust guides are in place they are diamond-honed in our honing station. 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. After resurfacing, the heads are ultrasonically cleaned to remove debris and oils from the machining process. The heads are then reassembled using GSC Billet S2 camshafts. The Stage 2 cams are intended for vehicles making 500-700 wheel horsepower. During the final assembly, the cams are matched to GSC Beehive Valve Springs and Retainers and GSC Viton stem seals then bench-lashed to a tolerance that is close to final specifications.

This Part Fits:

Year	Make	Model	Submodel	Notes
2008	Subaru	Impreza	WRX STI
2009	Subaru	Impreza	WRX STI
2010	Subaru	Impreza	WRX STI
2011	Subaru	Impreza	WRX STI
2012	Subaru	Impreza	WRX STI
2013	Subaru	Impreza	WRX STI
2014	Subaru	Impreza	WRX STI
2011	Subaru	Impreza	WRX STI Limited
2012	Subaru	Impreza	WRX STI Limited
2013	Subaru	Impreza	WRX STI Limited
2014	Subaru	Impreza	WRX STI Limited
2012	Subaru	WRX	STI
2013	Subaru	WRX	STI
2014	Subaru	WRX	STI
2015	Subaru	WRX	STI
2016	Subaru	WRX	STI
2013	Subaru	WRX STI	Base
2014	Subaru	WRX STI	Base
2015	Subaru	WRX STI	Base
2016	Subaru	WRX STI	Base
2017	Subaru	WRX STI	Base
2018	Subaru	WRX STI	Base
2019	Subaru	WRX STI	Base
2020	Subaru	WRX STI	Base
2021	Subaru	WRX STI	Base
2015	Subaru	WRX STI	Limited
2016	Subaru	WRX STI	Limited
2017	Subaru	WRX STI	Limited
2018	Subaru	WRX STI	Limited
2019	Subaru	WRX STI	Limited
2020	Subaru	WRX STI	Limited
2021	Subaru	WRX STI	Limited
2017	Subaru	WRX STI	Sport
2018	Subaru	WRX STI	Sport
2019	Subaru	WRX STI	Sport
2020	Subaru	WRX STI	Sport
2018	Subaru	WRX STI	STI
2019	Subaru	WRX STI	STI
2020	Subaru	WRX STI	STI