Trying to hammer a square peg into a round hole type of thinking here. Sorry.
Please, just sell the bov and get a simple BPV and set it up correctly running it in full recirc. If the stock BPV is not what you want, get the Forge and learn how to set it up and adjust it correctly.
I know you're stuck with the wrong piping for your IC, but that's not a good reason to mess up your AFR's with a dump to atmosphere when shifting. A tuning solution "adjustment" for this is just going to be a guess at trying to chase an constantly varying amount of dump under different speed, gearing and load conditions.
I'd be worried that since running VTA produces an overly rich condition, trying to tune around that would mean guessing at how much to lean out during a shift. I'd be worried that that adjustment might produce an excessively lean condition at other times. That might mean joining the zoom, zoom, boom club. That would be a lot more expensive and tragic than taking the time and spending a few more bucks to get what you need to run recirc.
As I think has been pointed out, if it's the "whoosh" sound and the turbo whine on light load spool up you are attracted to, you'd be surprised how loud even the stock BPV is, and how clearly you can hear spool up under light load, when you are running any aftermarket intake.