Magnaflow 4" SS turbo back system for 2003/2004 is p/n 17974. Do a google search on this p/n and you will find it for approx $475 or so delivered to your door.
Super easy install. Everything bolts right in place. I would get the SS band clamps instead of the u-bolts for approx $9 each.
You can't go wrong with the Magnaflow or the MBRP system. If you want the MBRP system p/n, please let me know.
I chose the MBRP over the Magnaflow only because it was 3 pipes vs. 4.
I had the Magnaflow muffler only before I upgraded to the MBRP SS system and the Magnaflow sounded like a big block gasser at idle with no drone while towing.
The MBRP has a weird "thup, thup, thup" sound at idle but may actually sound better at highway speeds.
Hope this helps,
Louis