Dan, where is the pressure source for the wastegate coming from?
I found on my old setup with no BOV, if I ran the pressure source anywhere pre throttle bottle, it lagged a bit coming back on boost. If I ran it post throttle bottle, it came back on boost really hard.
From what I could figure, when shifting, boost stays above the wastegate limit as it "spikes", and this allows what ever exhaust gas is flowing out of the motor, to go around the turbo if the wastegate pressure source was pre throttle body. If I put it post throttle body, because the plenum went into vacuum it would pull the wastegate shut again forcing what ever exhaust gas was flowing through the turbo, so keeping it spooled up a bit more.
Give it a go and see what you find.