running the bov has nothing to do with your TB the problem is a vortech kit is draw thru which means the air is metered from the moment that it gets sucked into the s/c. Metered air can not be vented into the atmosphere it has to be recirculated. If you converted to a blow thru setup (usually MAF in your fenderwell) you can run a BOV anywhere BEFORE the MAF. non metered air can be vented with a BOV... just remember this.
BOV = Blow Thru
BPV = Draw Thru
if you are needing a larger BPV (Bypass Valve) go with the procharger red top race valve and recirculate it back into your intake..