I've had some fluttering which was caused by the BOV rapidly moving up and down. At first I had thought an exhaust leak was the culprit, but it turns out that the Valve was extremely dirty. This caused the Brass valve to rub on the metal surrounding BOV. After cleaning the inside of the BOV and lightly lubing it, it works without a problem. So my message to all of you with this BOV, make sure you clean it every few months and check to see if there are any deep scratches.