According to Vortech, any supercharger producing over 6 pounds should run a BPV or a BOV. I say definitely run one. The deciding factor which type BPV or BOV is dependant on where your MAf sensor is going to be. MAF before the supercharger, you will need a BPV. MAf after the supercharger, aka slot style, its up to your preference. The standard bosch bypass is recomended for 6 to 12 psi according to Vortech. Anymore boost than that, and they recommend a valve that can flow more. Will the standard bosch bpv work for more boost, it has on my car that makes 16 pounds. Be aware that the standard bosch bpv cannot be adjusted. What does that mean??? Well, until your engine goes to 0 inch vaccum, the bpv keeps recirculating instead of building boost. This means, the car will have to be floored before the boost comes on. Higher quality units, both BPV and BOV can be adjusted to stop diverting air before 0 inches of vacuum. The higher quality ones will also dump more air in the case of a bov, or recirculate more air in the case of of a bpv when you suddenly let off the throttle, keeping pressure from slaming into the closed throttle body and reverting back into your supercharger impeller.
So what are the benefits of a BOV. All excess uneeed air created by the supercharger would be dumped directly to the atmosphere, so the routing of another hose back into your powerpipe is unneeded. Since air being passed through the supercharger is being compressed, it also is being heated up by the same process. Since the BOV's dump to the atmosphere, this already heated air will not be passing through the supercharger again, which would result in further heating of this air. This in trun leads to cooler IAT temps than vehicles equiped with a recirculating BPV.
Benefits of the BPV. The biggest advantage is the quietness of a BPV. Since they recirculate the air back into the intake plumbing before the supercharger, they are alot quieter. A BOV, is pretty loud when it is dumping air to the atmosphere, which is always except when you have your foot in the gas. Also, with a BPV, you can instantly tell if any or your post supercharger plumbing comes lose by the instant blowing sound you will hear. This sound is the same sound that a BOV makes constantly. Ill upload a video of the noise my car makes with the standard bosch bypass valve venting to the atmosphere. You can hear the blowing sound of air from it along with a little whine of the supercharger.
[video]http://s653.photobucket.com/user/kb1982/media/DSCN0762_zpsc254f5b2.mp4.html[/video]