If your looking for a spinning "tornado" intake product. Check out the Airiad helix bore throttle body spacer. It is a post throttle body product which means it works with all throttle angles. The tornado is a pre throttle body product that works best at or near WOT. I sell these spacers in my store and on the 6.0 motor they generally result in 1 mpg improvements with 8-10 hp gains. The Chevy 6.0 is the same as the Hummer. There will be some throttle cable brackets that you will not use. I see them for $95. Forum rules do not allow me to advertise. Therefore I will not sell to anyone as a result of this post. I am just offering free information to fellow H2 owners.
http://www.airaid.com/200-514_chevy.asp
Dan from Alabama
If I did not have a supercharger I would have had a Airaid helix bore throttle body spacer installed the first day I owned my H2.