as a v6 you aren't going to get the rumble as you are wanting. These v6's have more of a higher pitched sound on acceleration. I would recommend flowmasters. But that is only because I have experience with them on previous vehicles.
I ended up putting on two original Flowmaster 40 Series Mufflers. They were installed by Mike at Orange County Muffler. We both could not believe how loud they were on this car. The problem was they were too loud and the pitch a little too high so it was uncomfortable to drive and we put the original mufflers back on.
I spent lots of time on the phone with Flowmaster and Magnaflow. Both companies basically had no idea what would work best on teh 15 Charger cause its too new. Magnaflow is expecting to finish testing a custom catback system in the next month and after they they will have recommendations for mufflers as well.