Flatirons Tuning IAG Air Oil Separator Bundle (02-07 WRX, 04-07 STI, 04-08 FXT)

When upgrading your Subaru with an Air / Oil Separator (AOS) most of your PCV system hoses are replaced with the included lines, but not all. We've found most of the pcv hoses that are not replaced and made them available to you to add with your purchase of the kit. Depending on the vehicle, it should come with PCV hoses coming off the valve covers that connect with the lower cross over pipe. Also included are the hoses for the purge valve.

We also highly recommend getting the 3MI Racing Drain Hose with the kit because of the great improvement in the AOS drainage system. There is a direct pathway down into the turbo drain. Which we do have the option available here. There are 2 types offered depending on your turbo setup. Stock location turbo vs rotated location.

IAG Air / Oil Separator (AOS)

The IAG Air / Oil Separator (AOS) is a smart upgrade for your Subaru. Developed through years of testing on standard and competitive applications, the IAG Air / Oil Separator offers unparalleled protection for your 2002-2007 Impreza WRX, 2004-2007 STI or 2004-2008 Forester XT engine. Our AOS design incorporates a 1-liter cast aluminum swirl pot canister that significantly improves oil separation from the PCV system before returning PCV gasses to the intake. Constructed from a lightweight, yet durable aluminum housing, the IAG AOS offers improved ventilation and incorporates an intelligent baffle design that sets it apart from the competition. The IAG AOS works with all fuel types, improves crankcase ventilation, and seamlessly integrates with standard ECU settings.

3MI Racing Hose

Put simply this hose is used to improve the oil return from your AOS so that it can better perform for you.

So what's going on?

Many drain hose installations have the drain hose close to horizontal or with very little vertical angle. Under acceleration this prevents the oil from freely draining back to your sump. It is also well documented that EJ engines, under heavy cornering, push oil into the heads and can lead to excess oil entering the AOS. Additionally, this eases installation of the drain hose as many times it is inadvertently installed incorrectly by people who do not have experience.