BOVs don't work on boost, they work on vacuum. When you close the throttle this creates a vacuum in you intake manifold (after the closed throttle butterfly). This is connected by a tube to the upper side of your BOV which opens and releases the pressure (before the closed butterfly).

With a centrifugal SC the BOV is almost always open except when you press the throttle (open the butterfly).

 

Thank you sideways, I just want to get everything squared away before I get back!

And Aus, that is a great explanation. thank you for your input. I hate being retarded sometimes.