Yukon Flex Fuel mods

I know that starting 2002 all Yukons and Tahoes came out with the flex fuel engine noticeable by the eight letter in the VIN to be "Z". These vehicles have a lower MPG that the "normal" gas engines. I've read many forums about people having flex fuels and complaining of spending a lot more on gas.

So, my question is: Can you re-program the computer on these flex fuel vehicles so the engine can be in the "normal" state? If so, how?

Appreciate any inputs.

Omar Diaz
Sugar Land, TX