Muffler
I am using the Dynomax Super Turbos.
I have a 318 in the car, dual exhaust off the stock 273 manifolds,
and a Mopar .435/.450 cam.
I suggest you put some sound deadner uner the rear seat,
it will help with interior resonance, no matter what mufflers you use.
http://www.youtube.com/watch?v=Ud8mci4rjFU