I really didn't mind the sound of the stock GT mufflers. The problem was that my winter car, a Subaru, had bigger exhaust holes and more of them. So, I went to the GT500 quad mufflers. Now I feel much better about myself.
As far as sound, I think they are great. Louder than the stock but nowhere near something like Roush. A definite decent compromise.
I guarantee I will never change back. (of course, the single hole would look terrible with the quad valance so it's not an option anyway.)
Nice picture, thereaper.
All the best.
2014 Gray Mustang