I am still trying to decide what to do to my sytem to get ride of drone and make it deeper. I want it a little louder than stock and cant here anyone elses 5" system. My ???????? is that my buddy at work has a 04 CTD and has a aeroturbine on his with the cat still on and his is quiter and deeper than mine and no drone. Mine is 5" turbo back and no cat with pro flo muffler. Is the muffler making it sound different or what?