Just turning off the GM torque management nannies and correcting the air fuel ratio yielded  17rwhp more power and gains across all rpms and 28lbs of torque at all rpms all while still running 87 octane fuel.   Since this truck pulled 255rwhp with stock programming and these 2014+ L83 are rated 355hp and 383TQ.  a 28% drivetrain loss which with that size wheel and tire on a 4×4 is not unrealistic puts that 255rwhp correct for 355 flywheel hp but on that torque number its closer to 22% so it may be because of the 87 octane in this truck that it didnt make a matching 22% rwhp number which would be 276rwhp or closer to what it made with programming corrected.  regardless programming these new L83 5.3L yields a nice gain even on 87 octane fuel.