[Colt]

I just have the ER CP and Tial BOV on my car, and sounds similar to your experience. Not really loud, and I can never hear the BOV if my windows are up. If I give it gas and quickly shift to another gear I hear it whoosh loudly (windows cracked/down), but when driving normally I can barely hear it. I imagine if you do more modifications to the car and a tuner it would become more loud.

If you feel like it is hesitating releasing that can't really be a good thing. Did you buy it new or used?