Porsche 911 Turbo 996 1999-2005 TURBOSMART 25mm Uprated Dual Port Dump Valve BOVBrand: Turbosmart Part no: TS 0203 1022 Dual 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.