The Kompact Shortie Blow-Off Valve for the Focus RS has been developed with the Focus's high boost pressure in mind to improve performance and durability. Plastic OEM blow-off valves like those on the RS have a track record of failures - they leak and become brittle with age until they eventually crack, causing serious problems. Producing around 23 PSI of boost pressure in standard form, the Focus is already pushing the boundaries of its standard plastic blow-off valve - and there's not much room to turn the boost up before the standard valve struggles to keep up.Full recirculating BOV. The Plumb Back system recirculates all excess pressure back into the intake system. Great for enthusiasts not wanting to be noticed but wanting the performance and reliability benefits of a quality BOV.