I almost bought an 06 (new back then) single cab dually silverado (Vic red) with the 8.1.
Not to pull anything, just because I wanted to slam it and stuff some big rig wheels under it. I still wish I had done it
I regret selling it, to this day. She was really something. That is the most restricively tuned platform GM has. Once you do a tune, and open up the exhaust and intake on an 03-06, it is just incredible...it is the most dramatic change of any of my trucks I have done this to.