I agree. You'll never get the 3.8 to sound like a v8, but you can make it sound better. When I had my sixer, I had a stock GT exhaust system welded on. The 3.8 sounds pretty good with the stock GT mufflers. You can find them pretty darn cheap too.
Also, don't waste $$ on headers. The stock manifolds for split port sixers flow remarkably well. In fact, some of the v6 guys claim the dynos showed no real gains with headers until the engine was putting out serious power (blower, etc)
2002 Mineral grey GT 5 speed. Flowmaster 40's catback, Mach 1 grille delete, timing advance, push button starter, Bullitt pedals, FR500 steering wheel, K&N FIPK, Self ported upper intake w/ spacer, Pioneer Avic D3, MGW shifter, MM FL subframe connectors, Mach 1 springs, Bilstein HD struts/springs