I would go with an "Original Flow" Flowmaster from Summit Racing
3"inlet and dual 2.5" outlets. I am running this on my R/T and it has plenty of resonance in and out of the cab.My Flomaster cost me $69.00+$15.00 to weld it up.I want to warn you though,it is loud.
I cut and removed my original exhaust about 3.5" behind the #3 cat and somehow the cat got punched out (i wonder how that happened?) ,this made a huge difference in tone and volume.Then I got the flowmaster welded right up to the cat.Try it this way,you can always add pipe to the outlets to mellow the volume.ANY MORE FLOW THAN THIS AND YOU WILL START TO LOOSE LOW END TORQUE,WITHOUT SOME SERIOUS HEAD,INTAKE,& THROTTLE BODY WORK.Do the muffler & cat,its cheap and sounds insane,you will be impressed!!!!