From what i have learned from exhaust in my f150 4.6 is its only going to get so loud, i think it's from the small engine displacement. But i have changed my exhaust around 4 times on it and can say the smaller the tips, dual 2 1/2's it will be a higher pitch and trave far, with quad 3 in tips it was deep and mean with lots of rumble but did not carry as far. On my conti I'm going with true duals with a custom triple x pipe, minus the third converter, and a pair of flow master 40 series single in single out, and a set of porsche 944 tips, I'l post sound clips when its done.
So to answer your question, I don't know what mufflers to use (everyone has a different opinion on those) but I would pull all 3 converters and go with some big open tips in the back to get a deep rumble sound, it will definetly shake who ever is next to ya.