Yea, and where does that say the shaft will spin backwards? It doesnt. Im not disagreeing with it saying air starts going round the system the wrong way, it does, but the shaft will never spin the wrong way. Every starlet ive ever built hasnt had a bov, and plenty of high boost race engines are built without them aswell with no problems. Got to remember turbosmart have gotta sell their products one way or another. There not going to be saying, you dont need a BOV there poinltess, when its one of their main products.