That seems crazy fast for a stock turbo and stock injectors to me. Everyone's always talking about how quick the duramax is stock(ish)....seems like all the hype is related to the difference in stock transmission and the ability to tune with EFI Live.
My 6.7 efi tuned ran 13.80 leaving at 5 pounds of boost " couldn't leave any harder it was blowing the stockers away in 4wd" I generally leave on the street at 15 to 20 pounds
13.39 with a 1.81 60' at 99.** mph. Only mods are built transmission, AD150, gutted intake & exhaust. That's with 285/70/17 Nitto Terra Grapplers and a 2" leveling kit. I'm tempted to get some light 18" wheels and 29" drag radials..