I have been running United E85 In my FG turbo Since 2013 on 1000cc/min injectors, GTX3586, and Venom cat, dynoed @ 380rwkw on only 15psi due to a misfire. Currently run 18 psi and the injectors are maxed out @ probably 410rwkw.
E85 is fantastic fuel.
Issues:
E85 will dissolve the glue in the stock fuel filter. I fitted a KPM stainless high flow filter , That gave more power.
Cold starts can be a bithc ! I prime the fuel system with at least 3 Part key Turns b4 starting.
You will need a very big pump.. I ran a single in tank Walbro 460 with a 16v booster and Pump died one 0° deg night, 20kms from home. Problem with these boosters, is that pumps have inertia , and my 5psi hobbs switch to trigger the voltage boost, did not get the pump upto speed fast enough causing a stumble, that I fixed using a push button pump boost, that I use a second b4 putting the boot in - messy.
After the 460 died, I fitted the KPM twin Deusch 320 pumps in tank set up, this gave me much more power, and is good for 470rwkw On E85 according To KPM. 1000cc injectors are maxxed out now, I got bad advice and should have gone for 1500cc injectors.
I have never tried 50:50 98:E85 mix, but this sound like a good Idea given my lowish boost, but I will need a nother map loaded to make the car start and idle properly.