You will more than like not find any car audio forum with the same level of noise (ie. LOW) as this BBS. But for what it's worth, the best one I have ever read has been the forum at www.carsound.com

I can't recall if I have spent much time at the one from SoundDomain, but if the posters are primarily composed of the idiots that populate the pictorial profiles sections, then I wouldn't hold my breath in regards to its quality level.

Bruno