Crankcase Evacuation System MO25900Crankcase Evacuation SystemNOT To Be Used With Mufflers MO25900 25900 Reduces crankcase pressure throughout entire rpm range for increased piston ring seal, reduced intake charge contamination, and fewer oil leaks Track and dyno tests prove increases in engine performance Includes 2 each: Oil Separators Breathers, Breather Filler Cap Grommets, One Way Check Valve and Weld In Nipple for header collector, use with 5 8" Dia hose