So long as you have a nearly empty tank, and top-off with a full E85 fuel, you can use the Stage 2+ E85 v4.03 mapping on your vehicle.
- Run your tank nearly empty and head to the fuel station
- Pump as much E85 into your tank as possible
- Flash your E85 tune file
- Start your engine, and monitor STFT and LTFT on the datalogging screen
Please be certain to run your tank as empty as you can before switching to your new fuel an mapping.
I recommend that with your first two tank of E85 fuel, drive gently until your tank is nearly empty again, fill up with fresh E85 --again: do this twice before feeling confident to drive aggressively.
A flex-fuel kit allows you to pump and drive without being concerned over actual ethanol content because the ECU does all the work to adjust the tune based on ethanol amount.