Since you have an auto ST I assume your saying drop the shifter into 2 and then drive it, and move the shifter as if your actually shifting the gears ???
I know 2 St owners that blew up the tranny doing that because they did it on a regular basis.
IF you do it for snow, towing, or some other reason, that is ok, but to make it like your shifting the truck for the fun of it, i don't recommend doing it regularly..
Todd Z