SE... guessing 3.1L not sure about price on headers, but changing the resonator to a glasspack I've heard will give you some tone without killing it too much.
Honestly the 3.1 and the 3.8s just don't have a good sound unless you put alot of money into them, and even then its not a great one. Most aftermarket mufflers will make it loud, nasty, and drone badly. Usually the majority of people here leave the stock mufflers on (they flow well up to 300+ whp) and just do headers and a resonator replacement to get some throatyness too it.