You could try the technique I used in my video: record a video with your phone, holding the phone in your left hand against the steering wheel.

Turn the volume up and listen closely when I shift to 2nd during the acceleration that starts around 1:25: https://www.youtube.com/watch?v=2cyAZSDR_m8#t=1m25s

There's the "ssshhhHHHHHH" sound of the wastegate as I accelerate, then a "PUuuhhh" sound when I lift off the throttle to change gears. I expect the BOV will replace my "PUuuhhh" with a much more distinct "PSSHHhhh".