The ATR's sound great! I have the Hooker Max-Flo on my car, it's a single shot exhaust and it drones a little bit around 1,800-2,300 or so. It's not that bad really, but sometimes I wish my exhaust was quiet as a mouse and then when i want to i can open my dump pipe via DMH cut-out and be loud as ever.
Even with the Hooker muffler, i gain 3-5 pounds of boost with the open cut-out.
-Adam