Keeping unbiased & not dragging tunes into this (*cough*^^*cough*), essentially E85 gives us the ability to run very aggressive timing due to it's octane rating in our direction injection motors.
More Timing = More Power
There's a variety of blends that you can run (depending on which specific tune you want to go with ), but anything greater than 3 gals of E85 to a full tank of 91/93 will yield VERY
noticeable gains. ALL the tunes work with E85 & at this time there is no officially proven upgrade for the Fuel Pump or Injectors, so don't even concern yourself with those headaches.