Killer B FA20 WRX Air/Oil Separator w/ PlumbingFA MV3S C The Killer B Motorsport Air Oil Separator functions with only a vacuum source: the turbo inlet. This provides the vacuum source for the crankcase which is in no way affected by the turbo size. In fact, a larger turbo that draws more air will improve the separator function, compensating for increased venting requirements seen at improved performance levels. While small OEM turbochargers produce some crankcase vacuum under boost, larger