IAG Performance V4 Air Oil Separator AOS – Neon Yellow – 2004-2007 Subaru STI / 2006-2007 WRX

IAG V4 Air Oil Separator AOS — Neon Yellow — 2004-2007 Subaru STI / 2006-2007 WRX

Keep Oil Out of Your Intake
The IAG V4 Air Oil Separator (AOS) is designed to protect and improve the performance of your 2006-2007 Subaru WRX or 2004-2007 STI by intercepting crankcase blow-by oil before it reaches the intake tract. Developed after years of testing on both street and competition applications, the IAG AOS uses a 1-liter cast aluminum swirl pot canister to dramatically improve oil separation from the PCV system before PCV gases are returned to the intake. The lightweight aluminum housing provides improved crankcase ventilation and features IAG’s baffle design that outperforms competing options. Available in Neon Yellow.

DETAILS

• Color: Neon Yellow
• Material: Cast aluminum swirl pot canister — 1 liter capacity
• Designed for 2006-2007 Subaru Impreza WRX and 2004-2007 Subaru STI
• Prevents oil from coating intake components, intercooler, and silicone couplers
• Works with all fuel types including E85
• Compatible with standard ECU settings — no tune required
• Package includes: AOS canister, hose and fitting kit, mounting bracket
• Part number base: IAG-ENG-7185

How the IAG AOS Works
Oil in the intake tract leads to problems that compound over time. Oil coating the intercooler core reduces heat transfer efficiency. Oil on silicone couplers degrades the rubber over thousands of miles. Oil that makes it into the combustion chamber contributes to detonation under boost. The IAG AOS intercepts crankcase blow-by vapors before they reach the intake — the 1-liter cast aluminum swirl pot canister creates enough volume and turbulence to separate the oil from the PCV gases before those gases are returned to the intake. It works with all fuel types including E85, does not require ECU changes, and includes the hose and fitting kit plus mounting bracket for a complete installation.

Easy Installation
The IAG AOS installs using the included application-specific hose and fitting kit and mounting bracket. No permanent modifications are required to the engine or intake system, and the AOS is designed to work with both OEM and standard ECU settings — no tune changes needed. Installation typically takes 1-2 hours with basic hand tools.

Why Color Variants Exist
The IAG AOS is available in Black, Red, and Neon Yellow so you can match the color scheme of your engine bay. All three variants are identical in construction, materials, and performance — the only difference is the anodized finish on the aluminum canister body.

Why Choose IAG Performance

IAG Performance has been building Subaru-specific engine and drivetrain components since 2001, and in that time they have become the standard by which serious Subaru builds are measured. Based in Westminster, Maryland, IAG designs, machines, and assembles their products in-house using Haas CNC equipment and their own engineering team. Their catalog spans everything from short blocks and long blocks rated to 1150 BHP all the way down to the fuel system, oiling, and drivetrain hardware that keeps modified Subarus running reliably for years. Every IAG product exists because a problem needed a better solution than what was available — and the engineering shows.

The RallySport Take

The IAG AOS is one of the first modifications we recommend for any modified Subaru, especially turbocharged cars on E85 or running aggressive boost. The engine protection benefit is real and the installation is straightforward. IAG has been refining this design for years and the V4 is the most polished version yet — it is a well-sorted product that does exactly what it claims. If you are running a modified WRX or STI and do not have an AOS, this is the upgrade to do next.

Fitment