When I had an 00 V6 i purchased mac Shorties and a pypes dual exhaust system. It had hi-flo cats, Xpipe and turn down tips so it didn't look like crap with the bumper being cut up or tips sticking straight out from under the bumper.
The only thing that sucked was they were not a bolt-in product. They required some cutting. It sounded really good but not overly loud unless I went WOT or held high RPMs. It just sounded nice, like the V6 shoulda sounded. For loud, the cheapest is straight pipes with an X pipe.