just a dumb question... outside of the legal speak what are the benefits of losing the cat or just gutting it and leaving the shell??? also would it be better to lose the muffler and keep the cat??? I don't want it to end up a loud and obnoxious as my old 01 HO Cummins..

I recently put a 4" DPP system on my LLY. I also replaced the cat. converter with the optional front pipe. As far as noise goes, the sytem isn't much louder than stock, but you get a distinctive Turbo whistle on accelleration. I absolutely love it.

I wouldn't gut it, that's irreversable. Benifit is less resriction. How much less I don't know.