My car used to be tuned on E85. Its super knock resistant, allowed for shit tons of timing, and the increase amount of fuel required seemed to even spool the turbo faster. It usually requires 30% more fuel if running all E85, so I am assuming that a 30% blend would require roughly 9% more fuel overall. As long as your not already running > 90% IDC you should be fine just be rescaling the injectors and adding some timing. I don't know of anyone that has had a lot of success mixing it, but I guess it might be worth a shot.