High-powered modified Subaru engines tend to generate excessive blow-by oil and gasses. In these cases, an ordinary small catch can mayquickly fill with oiland not be adequate. Like the Radium Engineering Subaru Dual Catch Can Kitt, the AOS (Air Oil Separator) kit is responsible for keeping blow-by oil and other pollutants out of the intake pipe, manifold, turbocharger, and intercooler during all engine loads. The main difference is thatan AOS system returns what is collected back into the oil pan so there is no servicing required.

The AOS is constructed of three CNC machined sections that screw together and are sealed with O-rings.

Benefits
-Effectively raises the octane and increases engine performance with cleaner inlet air
-Prevents oil buildup in the intake or intercooler system walls, throttle body, intake manifold, etc.
-Lowers hydrocarbon emissions