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 |  SKU: IAG-ENG-H550DE

IAG Performance Street Cylinder Head Package

Subaru WRX/STI/FXT/LGT (EJ25)
$6,449.95
Loaded W/cams
Option
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Description

IAG 550 STREET CYLINDER HEADS PACKAGE FOR WRX/STI/FXT/LGT 

POWER RATING

The IAG 550 Cylinder Head Package has a power output rating of 550 BHP

ENTRY-LEVEL STOCK REPLACEMENT HEADS

The IAG 550 Cylinder Heads are designed to function as an entry-level replacement for stock OEM heads. If your engine has suffered a catastrophic failure which requires replacement of your cylinder heads, or if you don't have OEM heads to start with, the IAG 550 Cylinder Heads are a perfect solution. These heads also work great for cars with basic bolt-on parts up to 550 BHP. These heads include upgraded GSC standard size valves, GSC Viton Valve Stem Seals, IAG Stage 1 Valve Springs with Titanium Retainers, and OEM Keepers. GSC S1 Camshafts are available with OEM valve lifter buckets. We also offer an optional chamber modification service (see below) for EJ20 heads to allow use on EJ25 short blocks.

BUILT WITH 100% NEW COMPONENTS

Each IAG 550 Cylinder Head Set starts with new OEM castings from Subaru of America. The first step is to select your Year and Model of vehicle so that we may provide you with the right castings to fit your project. Next, you'll select whether or not you want to include our optional GSC camshaft package. If selected, these heads will include new GSC S1 Camshafts and OEM Lifter Buckets for valve adjustment.

The bare castings are visually inspected and then fixtured into our in-house Centroid 5-axis CNC Machine. 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. (Just in case you want to go bigger later.) Then the heads are fixtured in our Newen 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 Stainless Intake and Exhaust Valves, GSC Viton stem seals, IAG-Stage 1 Valve Springs with Titanium Retainers, and OEM Valve Keepers.

OPTIONAL LOADED GSC S1 CAMSHAFT AND LIFTER BUCKET PACKAGE

If you're planning for more power you'll want to select these GSC Power-Division billet S1 camshafts for your IAG 550 Head Package. These will not drop any low end power, and will create more power and torque across the entire RPM range. These are perfect for stock frame upgraded turbos or up to 500 WHP upgrades. Along with the camshafts we'll include all new OEM valve lifter buckets and set bench lash using our specially designed fixture. (FINAL LASH SHOULD BE CHECKED AND ADJUSTED ONCE HEADS ARE INSTALLED)

 

 

IAG 550 Street Cylinder Head Package Includes:

  • (x2) Brand New Subaru OEM WRX or STI Cylinder Head Castings
  • Multi-Angle Valve Job
  • Machined Cam Lobe Clearance
  • Resurface
  • Ultrasonic Cleaning
  • (x8) GSC 36mm (Standard) Intake Valves
  • (x8) GSC 32mm (Standard) Exhaust Valves
  • (x16) IAG Stage 1 Valve Springs & Titanium Retainers
  • (x16) GSC Valve Stem Seals

Optional Camshaft Package Also Includes:

  • GSC S1 Camshafts
  • (x16) OEM Lifter Buckets
  • Bench Valve Lash Service (Final Lash Should be Checked and Adjusted Once Heads are Installed)

 

 

Vehicle Fitment:

EJ25 engines will need chamber modification. Additional hardware may be required to install these heads to the following vehicles, including but no limited to ECU, Sensors, Ancillaries, Covers, Pumps etc.

  • 1999-2014 Subaru WRX (w/EJ25 Short Block Only)
  • 1999-2021 Subaru STI (w/EJ25 Short Block Only)
  • 1997-2013 Subaru Forester XT (w/EJ25 Short Block Only)
  • 2004-2009 Subaru Liberty GT (w/EJ25 Short Block Only)
  • 2004-2009 Subaru Outback XT (w/EJ25 Short Block Only)

Installation Instructions

Please review the PDF document below regarding installation, break-in procedures and warranty information.

PDF After Sale Document - Contains Shipping, Engine Care and Warranty Information

  • For use with stock cams or mild duration cams
  • Assembly and professional installation recommended.
  • Workmanship/parts warranty will only be available for professionally installed cylinder heads.

Fitment Table