The Killer B Motorsport Air/Oil Separator functions with a vacuum source only, the turbo inlet. This provides the vacuum source for the crankcase. It is in no way affected by the turbo size, in fact, a larger turbo that draws more air will improve separator function, compensating for increased venting requirements seen at improved performance levels. While small OEM turbochargers produce crankcase vacuum under boost, larger turbochargers produce even more. Drain back design assures that any oil accumulation ends up where it needs to be, in the oil pan, providing a consistent oil supply to the engine. Six stainless steel bolts on the top, make it quick and easy for inspection and cleaning. It is not heated, and we see no reason to add unnecessary cooling/heating (weight, complexity, increased install time, and increase the probability of something leaking), and this simple engineered form functions just fine without it. The Killer B Motorsport Air/Oil Separator should meet and exceed your expectations of how an Air/Oil Separator should work and function on a Subaru engine. Not only that, but it will also display some of the best eye-candy fabrication available. The Killer B Motorsport Air/Oil Separator is a product that you the enthusiasts, have been waiting years for.