If you're worried about how much more fuel you're gonna use, E85 isn't for you. You're going to use waaay more cause you're foot is going to be planted to the floor. It cost me more at the pump than my 91 tune does and I don't care. I'm never switching back.
I'm running a Walbro 255, ID1000cc injectors, stage 2+ at 23 pounds. I'm making 349whp & 417wtq. I got 80wtq just from the E85 tune.
Oh, and I carry 10 extra gallons in my trunk at all times.