I gutted the third CAT a few months ago during the summer. I had already deleted the muffler (and flapper valve) and installed some BBK Short tube headers. The exhaust sounds awesome IMO - not too loud and has just enough growl to sound good. I left the resonator on the stock exhaust for the time being. I run a custom tune using a SCT X4 tuner. I have not had any issues with throwing codes or service indicators on the dash. Running the 5.3 L83 in this truck. Next mod will be swapping the stock intake and TB for the 6.2L L86 intake and throttle body. Truck runs great and definitely has more "get up and go" then before, the tune alone made a huge difference.
