Start hacking! There are a multitude of ways of getting more sound. Most just replace the rear "resonators" with a straight through design. I would like to see someone try an X-Pipe Muffler in place of the "suitcase" muffler in the mid section.
I've actually come to enjoy my R/T exhaust. It's not loud by any means, but it does tell people it's NOT a V6 under the hood. I had a 24" magnaflow on my RAM and I loved that. It was just enough bark without being annoying to both me and the people around me.