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IAG Stage 5 AW20 Ported Cylinder Head Package (Cams / Rockers / Lash Caps Sold Seperately) - 15-19 WRX

IAG's Stage 5 Cylinder Head Package utilizes a CNC porting program for the AW20 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 AW20 FA20 WRX DIT OEM head castings, directly from Subaru of America. The bare castings are visually inspected, and the oem guides are pressed out. Next, the heads are fixtured into our in-house Centroid 5-axis CNC Machine, one of the most advanced pieces of precision engine machining equipment in the world. The Centroid CNC ports the intake and hard-to-reach exhaust "dog-leg" port runner. The benefit of CNC porting is, not only an efficient way of machining the heads, but it also offers consistent port results, which are hard to achieve by hand. Once the Centroid completes the porting process the heads are drilled to fit larger 1/2" or 14 mm head studs, which are commonly used in high horsepower builds. Following the drilling process, the OEM press-fit freeze plugs are removed to avoid a common known failure, in which they loosen and leak coolant into the engine oil, as well as externally. To eliminate this problem, each head is tapped and threaded plugs are installed. To improve airflow specially shaped GSC Manganese-Bronze valve guides that are pressed into place. Once all of the new intake and exhaust guides are installed 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 Ferrea Comp Plus +1mm valves. The cylinder heads' decks are resurfaced using our TS-3000 BlockMate, which cuts the aluminum to a smooth, even finish. To remove debris and oils from the machining process, the heads are then ultrasonically cleaned. Finally, the heads are reassembled using Ferrea Dual Valve Springs and Titanium Retainers along with GSC intake and exhaust valve stem seals.

Stage 5 Ported Head Package Includes:

  • (x2) Brand New Subaru OEM AW20 Cylinder Head Castings
  • (x8) Ferrea 35mm (+1mm) Comp Plus Intake Valves
  • (x8) Ferrea 30mm (+1mm) Comp Plus Exhaust Valves
  • (x16) Ferrea Dual Valve Springs, Locators & Titanium Retainers
  • (x32) Ferrea Valve Keepers
  • (x16) GSC Manganese-Bronze Valve Guides
  • (x8) GSC Valve Stem Seals
  • (x8) GSC Exhaust Valve Stem Seals
  • Threaded Coolant Plug Upgrade
  • IAG Performance CNC Porting
  • Multi-Angle Valve Job
  • Drilling for compatibility with ½” or 14mm Head Stud
  • Resurface
  • Ultrasonic Cleaning
Recommendations / Warranty:
  • Assembly and professional installation recommended.
  • Workmanship/parts warranty will only be available for professionally installed cylinder heads.



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