Apparently I was misinformed. I just went looked up a couple of sites and the biggest was a 6.2 offered for the Denali. I would go get another vehicle, but this one is paid for. I just want to figure out how to get as much HP and Torque as possible with out having to spend the 6k to 7k to supercharge the 5.3. Plus, I think driving a truck thats all motor is a lot more fun ! I could also get a 6.0 from a GTO or Corvette along with transmission and electronics and do that swap, which will still be cheaper than supercharging it. I have listened to a couple of GTO's with 408's from Texas Speed and they sound amazing !