My '04 has the silverline 4" turbo back system, and I can't tell much of a difference in sound. It's louder but there's not a lot of turbo noise. I'd like to remedy that. My Uncle and my neighbor has an '03 with the same system on it, and his sounds like a damn K.W. rolling out of the driveway. I know there are differences in the trucks because of year, but I don't have the turbo whine or the deep glasspack sound that I wanted when I payed for the system. I installed it myself, and it was all strait forward stuff. It wasn't rocket science at all, but maybe I missed something. Does anybody have any ideas?