I love the sound I have been hearing with them and will be installing mine ASAP once car is out of storage in approx 2 weeks. I already have the parts. To combat the cabin noise you could always do some dynomat or some other sound barrier in the trunk ara to help quite it down. I might end up doing this.
I also have been reading it helps keep the little annoying wheel well noises out when little stuff bounces around up in there. I always check for damage and there's none but some days those sounds like its hurting it, so I'd rather just not hear it. Lol
Evil sports - are you not liking them now? Or why are you asking if they get quieter?
though I don't see how a straight pipe setup could get quieter.....