My first mod was a catback with Flowmaster Super 40s. At first I didnt think it was loud enough! I didnt have any drone at cruising speeds and never once did I think they were too loud. I actually did feel a gain also since it was matched up with 2 1/2 piping. I was in the same boat as you by wanting the growl of the mustang but not wanting to pay the price of it bleeding your ears. Totally satisfied with what I have. As soon as I get my camera to stop being an ass, I will upload a short exhaust vid I did today.
