For a small amount of E85 to pep 95 RON upto being 97 RON equivalent

Fuelling:
Easily taken care of via a slight raise in fuel pressure to account for the increased flow if you are just talking about putting a small amount of E85 in.
I really cant see the point though when you can just buy 97 RON anyway, what advantage does it give you? Possibly you will save literally a few pence per litre, but not worth the hassle of having to always fill up at two pumps and get the right percentage mix etc, plus i would be wary of if it was mixing properly unless I did it outside of the tank


Timing:
You shouldnt need any changes at all, but obviously get it det checked and check your EGT's



If running pure E85:
Fuelling:
You will need a pump that is safe on E85, bigger injectors, your tank wont last as long per fill

Timing:
You will need a remap, as the timing requirements are very different, you should be able to get a lot more ignition into it

Engine changes:
It would be worth upping the compression