Originally Posted by tabetha

DV were NOT at all made for rally cars to stop "back spin", they were actually made for NVH, Noise Vibration Harshness reasons, and to help performance.
If the air entry could actually cause enough force to spin the turbo backwards, it would snap the shaft, it would also be amazingly effecient to generate this much boost that the inlet is ahead of the exhaust side.
The almost stalled air at lift off merely gets buffeted violently by the impeller with no dv, but it most certainly does not stop.
tabetha