My car actually had it a little bit on the stock spring too but its way more pronounced and annoying on the new low pressure spring setup. I'm not sure how you'd tune that out? It's a physical surge of air happening right as that valve closes (not open as I was incorrectly saying above). I can see using the accelerator pump logic in the tune to try and tune out the lean spike but it won't stop the surge which is a physical blast of air. Even tuning the accelerator pump logic seems worthless to me. Unless you stabbed into the gas pedal triggering it you wouldn't even hit the exact point of the valve opening. Keep us updated on how you attempt to tune that out goes.
I've been thinking about this a lot and something I want to experiment with is a restrictor in the line slowing down the valve operation. If the valve closed slowly instead of just snapping instantly you wouldn't have that jerk. The only side affect I'd have to see is when you're attempting to move out fast and nail WOT will the valve still move quick enough or will it cause a hesitation?
I have to pull the blower to replace injectors anyways so I think I may just tear it all apart and go back to the stock bypass valve. Perhaps I'll try the restrictor idea before doing that.
During part throttle cruising is really when a low vacuum valve is need so blower temps/iat2 are in check. I would have a low vacuum valve with cams in the 5-7in of vacuum range (really anything under 12in HG). Remove the spring add a threaded end cap(thread sealer) and plumb vacuum line to a Boost source so the valve will close under boost. At idle it will function like normal. Your original valve might have not been opening at idle with those cams you have.