GenV ProPort BOV unit. ProPort by Turbosmart is an all-new 54mm (2.13in) Blow-off Valve with a tiny footprint and massive flow. The ProPort flows 420 cfm, enough for 3500 HP, and is in a league of its own, standing 30mm (1.2in) lower than PowerPort while flowing over 25% more than the Market leading 50mm Raceport.