although that being said in a racing application if you flat shift or shift quick enough (without a bpv) you would still have inertia in the turbine and positive manifold pressure for the next gear. That's the only benefit, which you won't need for a street car / the average driver. I didn't have a bpv on my car for a while because the stock one was failing, but I upgraded to an aftermarket shortly after. The chirping was annoying and I'm not that much of a hoon to be smashing through the gears everyday haha