I had a 2010 R/T, and I added two super 44 mufflers and then had custom pipes added back from the mufflers. I loved the sound, friend had a SRT8 Challenger with the flowmaster full cat back and it sounded almost the same. Best thing was cost me only about 350$, 700$ for him!
Cut the two resonators off the very back by the tailpipes. Replace that with straight pipe. Cut the muffler out from the middle and put the flowmasters in there. That's what gave me the deep muscle tone.