Well my 4.5 lly sounded good, I regret not putting a muffler on it. At first I loved it but the drone eventually got annoying. I had a lbz intake and turbo mp. Downpipe, manifolds w/ 4inch exhaust. I would get compliments about the tone. People said it was distinct. I was going to install a ported and polished turbo with a different wheel when I wrecked it.
I can't wait to delete the Powerstroke because they sound pretty good without the dpf filter.
I'm not a fan of the cummins sound. Bunch of guys run them straight pipe around here and its just loud.
