Originally Posted by MoulaZ

I was under the impression all BPV are closed until TB closes, Intake manifold sees vacuum, and causes the BPV to open. In addition the charged air has no where to go and pushes up against piston inside BPV aided by vacuum on the other side to escape.

This is also what is throwing me off about your setup. How does the unit remain open but close when accelerating? Is the piston/spring/diaphragm moving in reverse or something?

I know the whole venting to atmosphere here is a non-issue as in this setup your MAFs are much further down so the air would have escaped before being metered and causing issues.