Turbosmart Kompact Dual Port 25mm Blow off ValveDual outlet type BOV. Dual Port vents both to the atmosphere and back into the air intake. Ports with sequential timing allow quieter operation during normal driving, while getting all the benefits of a vent to atmosphere BOV under race conditions. Easily converted to a full atmospheric or full bypass unit by using supplied port blanking plug. Please note; that for twin turbo applications, such as the Audi S4 2. 7L (B5) 97 01, this will require two