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. Each IAG 550 Cylinder Head Set starts with new OEM castings from Subaru of America. 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.
This Part Fits:
| Year |
Make |
Model |
Submodel |
Notes |
| 2018 |
Subaru |
WRX STI |
Base |
|
| 2019 |
Subaru |
WRX STI |
Base |
|
| 2020 |
Subaru |
WRX STI |
Base |
|
| 2021 |
Subaru |
WRX STI |
Base |
|
| 2020 |
Subaru |
WRX STI |
Kanrai Edition |
|
| 2018 |
Subaru |
WRX STI |
Limited |
|
| 2019 |
Subaru |
WRX STI |
Limited |
|
| 2020 |
Subaru |
WRX STI |
Limited |
|
| 2021 |
Subaru |
WRX STI |
Limited |
|
| 2019 |
Subaru |
WRX STI |
S209 |
|
| 2018 |
Subaru |
WRX STI |
Sport |
|
| 2019 |
Subaru |
WRX STI |
Sport |
|
| 2020 |
Subaru |
WRX STI |
Sport |
|
| 2018 |
Subaru |
WRX STI |
Sport-tech |
|
| 2019 |
Subaru |
WRX STI |
Sport-tech |
|
| 2020 |
Subaru |
WRX STI |
Sport-tech |
|
| 2018 |
Subaru |
WRX STI |
STI |
|
| 2019 |
Subaru |
WRX STI |
STI |
|
| 2020 |
Subaru |
WRX STI |
STI |
|
| 2021 |
Subaru |
WRX STI |
STI |
|
| 2018 |
Subaru |
WRX STI |
Type RA |
|
Specifications:
| Description_SHO |
550 Cylinder Head |
| Description_INV |
IAG 550 Street Cylinder Head Package |
| Description_ASC |
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) |
| Description_ASC |
For use with stock cams or mild duration cams. |
| Description_ASC |
Assembly and professional installation recommended. |
| Description_ASC |
Workmanship/parts warranty will only be available for professionally installed cylinder heads. |
| Description_KSW |
IAG Performance |
| Description_LAB |
550 Street N25 Cylinder Heads Package w/ GSC S1 Cams & Lifters |
| Description_DES |
IAG 550 Street N25 Cylinder Heads - GSC S1 Cams & Lifters |
| Description_APS |
Subaru: WRX STI 18 - 21 Base / Kanrai Edition / Limited / S209 / STI / Sport / Sport-tech / Type RA |
| Description_EXT |
IAG 550 Street N25 Cylinder Heads Package w/ GSC S1 Cams & Lifters for 18-19 STI Type RA, 19-21 STI |
| Description_MKT |
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. Each IAG 550 Cylinder Head Set starts with new OEM castings from Subaru of America. 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. |
| Description_FAB |
New Head Castings with Upgraded GSC Standard Size Valves, IAG Stage 1 Valve Springs with Titanium Retainers |
| Description_FAB |
Power: The IAG 550 Cylinder Head Package has a power output rating of 550 BHP. |
| Description_TLE |
IAG Performance 550 Street N25 Cylinder Heads Package with GSC S1 Cams & Lifters for 18-19 STI Type RA, 19-21 STI |
| Description_DEF |
Engine Cylinder Head Set |
