I am just going to start with mufflers on '04 Mach. Does anyone have any they really like or really hate? I don't want something too loud. Does anyone have Bassani? I've heard good things about them.
Here is a good website with a hundred different exhaust sounds and lots of info. if you have not seen it yet.
Incidentally, my ford dealer was fine with me installing a muffler (or cat-back), but said that the exhaust and a K&N filter were the only mods. allowed.
http://www.mustangexhaust.com/