Most exhausts will be loud on the NA from 1500-3000 RPM, except for the HKS. I used to have a Greddy SP, which was fairly quiet, but it was a circa 1995 model, and I think it has changed a bit since. It used to be dual tip with a smaller muffler can; now it's a single large tip with a larger muffler. My Borla now is relatively quiet, but there is still some resonance at low RPM's. It can get a bit annoying at highway speeds. If you live in a climate without snow and don't need stainless, your best bet for noise may be HKS.