I have a 2012 Sierra with a 5.3L motor, 6 speed tranny, 3.42 gears, Goodyear Eagle LS-2 275/55/R20's, custom tune, true dual exhaust and a K&N CAI. I've put it in 2wd, disabled the traction control and StabiliTrak by pressing the button on the dash, manually put it in 1st, pulled the ABS fuse and put it in tow assist mode but it refused to spin the tires even a little. It'd only rev up to around 2000 rpm while pressing the brake and gas. The throttle response is shit and the truck is just plain gutless until it hits 4k RPM's.

Performance upgrades:
TruckExhaustKits.com
2.25" Aluminized Steel Dual Exhaust Kit
Ebay.com
Flowmaster Super 40 Series Muffler
Dual Inlets 2.50", Dual Outlets 2.50"
AutoAnything.com,
K&N 77 Series Metal Intake Kit
Diablewtune.com
DiabloSport Trinity T1000 tuner

Installing the custom tune:
   • Tune Installation On A GM Truck  

PROBLEM SOLVED!!
   • 2012 GMC Sierra 3.42 to 4.10 Gearing ...  

Check out these other videos I've taken of the truck:

K&N Cold Air Intake Installation:
   • K&N 77 Series Cold Air Intake Install...  

Sound of before and after intake install:
   • Before and After Installing a K&N Col...  

120 MPH Run:
   • Before and After Installing a DiabLew...  

Exhaust Sound Flyby's and Hard Acceleration:
   • 2012 GMC Sierra Exhaust: Flyby's and ...  

SVM Mobility Door Opening Demo:
   • SVM Mobility Truck Door Opening Demo  

Check out my Facebook page for behind the scenes stuff:
www.facebook.com/mncarguy