mranlet- A couple of years ago I would've been on the same boat as you when it comes to BOVs. But after having many customers running them on their cars and coming back with all sorts of feedback, I've actually learned a few things.

As you know the Synchronic BOV is always open with vacuum. A pain in the ass right? Well one thing that many of our circuit racers started to tell us is that after the BOV was installed, the motor started to pull more vacuum. Well, since it is open under vac it will relieve pressure right before the throttle when the throttle is shut (when installed between the IC and throttle plate). This creates a greater pressure differential across the throttle under heavy vac and lets the engine pull more vac under decel.

How is this good? This allows the brake booster to have more vac under heavy braking and improves performance at the track for circuit racers.

So, sometimes there are side-effects that you don't even design in that come up with all the different applications that the product is used on.