Many 80's turbo cars ran no recirc valve from factory, St165 GTFOUR, Mitsubishi cordia, starion, sigma GSR off the top of my head, for 3 years i ran no BOV on my legacy with TD05. The thing is, the compressor is spinning when the throttle closes, but the exhaust flow is also stopped at the same time, so all that's left is the inertia of the wheel assembly. Recirc helps maintain and thus recover compressor speed when the throttle reopens, that's why all OEM cars have it from the 90's on