There is a difference between loud and sounding good. A nice catted pipe with a good set of mufflers and headers will be louder than you think. My 98 has shorties, BBK catted H and Dynomax chambered Thrush mufflers (would not have been my choice but the PO had them on the car and they've grown on me) and its definitely loud enough without being obnoxious and having a nice tone. I know for a fact if I put an OR pipe on there it is going to drone like crazy. As it stands, its just barely quiet enough at 2300rpm and 75mph on the highway. Also good cats don't suck up a ton of power like ppl will make you think. Mabye 1hp to the wheels...maybe.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.