After years of being asked to develop a Killer B Motorsport Air/Oil Separator, we are proud to announce we have released the FA20 WRX Air/Oil Separator. This is a product we've been asked to develop for many years, and in that time there has been a lot of research, engineering, simulations, development, testing, (and repeat), with several different Subaru engines and build types, including stock engines. This process has occurred within many different seasons, exposing the Air/Oil Separator to extreme environmental and driving conditions (daily driving, auto-X, drag racing, dyno testing, etc.), as well as exceeding 700whp. The goal of this product is simple. To function as its Air/Oil Separator name implies: to remove oil, in liquid or vapor form, from the vented crankcase gasses. Simple in premise, but functionally there's a bit more to it. Oil droplet sizes vary with differing pressure and velocity conditions. Different engines vary in their venting characteristics. Street cars vary from track or performance elevated engines. The list of variables goes on, making acceptable function and performance a difficult challenge. Performance must be spot on, but the effect on the engine's operation will be unchanged at least, and improved at best. We prefer the latter. This is accomplished by using a design that has no restrictions, media or baffles, to reduce the flow potential of the crankcase and head vents. Under positive boost conditions, it will produce vacuum in the crankcase. The benefit of this is improved evacuation of crankcase gasses and the many other benefits that can be had with crankcase vacuum; improved ring seal, reduced oil consumption, and improved power potential. 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 effected 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 for quick and easy inspection / cleaning. It isn't heated, and we see no reason to add unnecessary cooling/heating (weight, complexity, increased install time, and increased probability of something leaking). 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 function on a Subaru engine. Not only that, 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.