I just put a K and N CAI on my truck and it made it run ALOT better ( in my mind at least, lol.) Really helped on the get up and go. but anyways! I want a muffler to compliment it, I want pretty much the quietest muffler you can get. I've been reading alot about the flowmaster 50 series, but how loud is it in the cab? is there any other "quiet" mufflers that still get the good sound??