Remember guys, surge is caused by a high pressure ratio and low flow. This doesn't mean the car has to be in boost for surge to occur. Revving the motor up while still in vacuum does speed up the turbo a bit, and closing the throttle quickly will effectively make flow zero giving the turbo a chance to build up a positive pressure ratio. That being said, I highly doubt it will build a high enough pressure ratio to actually surge.
It's probably just due to the fact that the BOV is a knockoff.