Ever since I've had my car, my Tial BOV would not vent immediately on throttle lift. It would go pur pur pur pur POOSH. The pur pur noises are from the compressor surging.

At first, I thought the problem could be solved by getting a lighter BOV spring. Didn't help much. At the time, I was using a small vacuum port for a signal source. I thought maybe I needed a larger line so I Tee'd the BOV signal into the brake booster line. Didn't help. I hoped the problem would go away when I ran more boost. After going from 9lbs of boost to 17, it still purpooshed.

Recently, I freed up my the PCV port on my intake manifold. I plugged up the BOV signal to that port and took a drive. On throttle lift, it vented immediately at all boost levels.

My conclusion is that the Tial BOV design needs a signal from a dedicated, large diameter vacuum port to vent properly.

 

I have the same problem with the "top" chamber on my wastegate.

 

Regarding your quote, I read that and that's what led me to tee into the brake booster line. The caveat is that it should be a dedicated line since the signal is time sensitive.

So what problem does that cause? Boost spike?