The TRX has two mid mufflers, like the Chally or Charger, but no rear resonators. SRT put 4 mesh cut outs near the rear of the exhaust. This allows the noise to "come out" before reaching the rear tips and it quiets the overall exhaust and reduces drone.. Apparently GM is doing something similar on their trucks. My Rebel did not have this, nor does the wife's TH. So a quick fix is to just put clamps over them and it increases the exhaust dB by about 5 or so.
I have 2 new dynomax bullets leftover from my old HC. I may throw them on the TRX in place of the mid mufflers and see how that sounds. I haven't found any other owners who have done the swap yet for comparison.