the only thing you need to do right off the bat is minimum 60lb injectors (some get away with 42.5 but not too long) and a tuner...

and if mph=mpg in your comment then ~30% drop... ish.... I went down more like 20%...

but I assume youre running premium, and (around here anyway) e85 is about a constant 25% cheaper than the premium so its really not costing you THAT much if anything... if youre lucky (like me) youll end up saving money...