Welcome to the wonderful world of turbo 4's and their tunes. great, isn't it? Honestly, I never saw much of a change in MPG between factory and stage 1 or 2 with my driving habits. the only reason i've seen a considerable jump the last week or so is because i've been driving like my grandpa to try and keep the gas budget down. If you're not hammering on it all the time you likely won't see much of a change, possibly a slight bump if anything. so good news is you won't see a sudden drop to 19mpg or something, if you do you've got other problems...