Flatirons Tuning IAG Air Oil Separator Bundle (08-14 WRX, 08-21 STI, 05-09 LGT)

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 Performance Air / Oil Separator (AOS) is a smart upgrade for your Subaru. Developed through years of meticulous testing on standard and competitive applications, the design of the AOS offers unparalleled protection for your engine. This AOS features a 1-liter swirl pot canister made of cast aluminum. This construction significantly enhances the separation of oil from the PCV system before the PCV gasses are directed back to the intake system. The Air Oil Separator features an aluminum housing that has superior ventilation, and it incorporates an exclusive baffle design that sets it apart from the competition. The IAG AOS works with all fuel types, optimizes crankcase ventilation, and seamlessly integrates with standard ECU settings, so no tuning is required.

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.