New 2020 GMC Truck purchased and while checking out the massive exhaust I noticed the extension on the end of the pipe giving the impression of a much larger exhaust. To my surprise the end of the pipe necks down to a 2 3/4" opening. That has me worried, on my old truck I had an exhaust temperature gauge so I could monitor the heat on a long pull. The new truck has no exhaust temperature readout anywhere I can find. It's the LP5 Duramax rated pretty high in torque and hp. Is 2 3/4" enough opening to get all the exhaust gases out without overheating the turbo? Can the opening be increased without setting any codes?