"Z32 TTs come from the factory with recirculation valves. They basically take excess boost that is made when the throttle plate is closed and plumb it back into the intake system allowing for better response. Typical blow off valves simply "blow" the air out into the atmosphere to be wasted. Ideally, you can make a BOV that recirculates back into the intake system. There is nothing wrong with keeping your stock recircs, they actually help you. Unless, you want that cool "sneezing" sound, then go on right ahead! Remember it's only our suggestion not gospel."