Local fella has a 6.0 CC SB dually... all black, sharp lookin' truck... the sound of his truck is awesome... not loud, but healthy... I roll my windows down to listen to it go past! My truck is straight piped, and his with muffler is louder wistle than mine... at least from the drivers seat of my truck! I have no idea what my truck sounds like, no one else ever drives it!