I love magnaflow's.
I have a 2 into 1 on my 71 w/ stock 302, it has a nice rumble, but never gets too loud by any means. I have driven it 2+ hours and it never got old... granted i run topless all the time...
I have dual magnaflows on my 07 charger w/ aftermarket duals and same thing, rumbles, but never loud/ obnoxious