What type of performance upgrades help the 6.2 other than exhaust and air intake upgrades?

I would suggest that you make a run to the local "speed" shop. I know that there are programmers, Turbos, Injectors (with fuel upgrades), as long as the ones you mentioned, Your local spped shop will have a bunch of info and beable to tell you what is availble right now, You do have a 2008 so it might take a few months before there is more upgrades out there. Best of luck, hope this helps. Cheers

Agreed. There may also be dealer-available upgrades. MOPAR sells "Stage 2" kits, etc., which tune the vehicle for you, and won't void your warranty. Not sure about GMC but I would start at the dealer parts department and work outward from there.

Headers. Computer tune. Turbo. High performance fuel pump and injectors. Or cam.