PhoenixDownVII

No, you just remove the pipe that takes your ventilated turbo boost and recycles it back into the intake-tubing.



Most aftermarket ones come with a plug to "plug" the hole made by not having a tube run back to the intake manifold anymore...



Doing that to my Mr2 Turbo made the car want to stall between shifts though....did it to my friends MKIV Supra TT...not cool.



It makes the mixture change (lean/rich) which isn't a good idea on Rotaries am I wrong? (about the change in mixture).

Danomite

MAF (mass air flow) meters the incoming air, pre-turbo and compensates fuel accordingly. MAP (manifold absolute pressure) meters, well manifold pressure and does the same thing. If you have a MAF system then venting excess boost pressure will cause a rich condition when the BOV or BPV is actually venting. A MAP system should not be affected by venting boost pressure to atmosphere because it meters pressure after the throttle body. I switched out my stock BPV's to twin HKS BOV's on my S4 and had better response when shifting w/o any fuel mixture problems, and that car uses a MAF system, eventhough everyone said it would run rich (which in theory it will)