NMS EJ25 Billet Valve Cover Kit w/ Integrated Air Oil Separator (AOS) - Subaru WRX 2006-2014 / STi 2004-2021 / FXT 2006-2013 / LGT 2006-2009

Introducing our NMS EJ25 Billet Valve Cover Kit, with built in extra cooling features along with an industry leading Air/Oil Separator. Subarus like all flat engines, blow a lot of oil out of the crankcase in their blowby gasses. This is always a problem with performance flat engines like Porsche or Subaru. The fact that the WRX and STI are turbocharged just makes the issue worse because turbo engines produce more blowby. When oil is ingested into the engine via the crank vents and PCV system, it contributes to detonation which will damage your engine, especially if is turbocharged. Oil can accumulate in your intercooler, reducing its effectiveness. Subarus blow so much oil that they can run the crankcase dry in one track session which obviously causes engine damage. Because of this, there is a big market for Subaru air oil separators. Nightmotorsport has another solution to help remove the oil from blowby gases internally by incorporating an improved air-oil separator into their bille