I picked up the stang yesterday from getting o/r x-pipe with mello-tone mufflers installed. Sounds great, will get some sound clips whenever the weather gets better. Since getting the leak fixed I can hear more of what the car is doing. The exhaust isn't very smooth sounding, kind of like a spudder whenever I give it some gas. Can anyone pin-point what might be the problem. When I first got the car I thought it might just need a tune-up but that didn't fix it either. Any help would be appreciated!