Hmm.. I think I might know what you're talking about. Make sure your filter is on tight. My car was doing it too but when I checked the filter slipped off my intake tube. My car makes a fluttering type sound too, but boost pressure doesn't bounce. So I'm not real sure what yours is. I would guess it does have something to do with the wastgate or bov/bpv
---------- Post added at 08:33 AM ---------- Previous post was at 08:26 AM ----------
Get ahold of your tuner and then let us know what you find out.