A mate of mine is running it in his very tough corolla (track toy), just by switching he has gained 20hp (atw) at 6k rpm (which is a pretty hefty jump for an NA engine), all his temps have dropped considerably, i.e coolant etc, due to the better cooling properties of alcohol over petroleum based fuels, and you can tune your timing a lot more aggressively to take advantage of the properties of the fuel, now the downside, he is running 1000cc injectors to cope with the additional fuel required in order to maintain a stoichiometric AFR, ethanol's stoichiometric ratio is 9:1, petroleum is 14:1, as as mentioned the majority of parts in your fuel system are not designed to run alcohol based fuel through them, you may not have any issues doing this, but it is worth considering.
So yes a tune will be critical, and you may max out the stock injectors and fuel pump, and being a DI engine I would imagine all these types of parts are outrageously expensive.
Heres some good reading on E85,
E85 in standard engines - Wikipedia, the free encyclopedia
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