I have to totally agree with Zef here, the tuner is probably by far the best purchase you can make. I think it would be cool to have some sorta contest to see who can pick up the most fuel economy from tuning alone. There is just a lot of possibilities with a tuner.

I work with a guy that is using EFI Live on a Chevy truck and has picked up somewhere in the area of 5 mpg with tuning alone.