You might want to have this thread moved to the 2011+ v6 section for more replies.
I would say that if you don't want raspiness stay away from an off road x pipe. I'd stick with the long tubes, a prochamber or h-pipe and the axle backs.
I have heard the Roush axlebacks on a 3.7 with factory manifolds, cats etc. and they sounded pretty good.
12 Black GT500 SVT PP l VMP TVS l JLT123 l O/R X l 28x11.50Rx15 M/T Street R's l BMR Suspension l Recaros
03 Sonic Blue 3.8 / 17 Magnetic Fusion Sport 2.7 EB