E85 is not available in my area.

On my previous 04 cobra I had good luck with the use of some torco just for some extra octane insurance.
Only down side was the orange plugs and most likely orange colored combustion chamber, but I never noticed any loss in HP from multiple dyno runs. Just need to change plugs more frequently.

Anyone use torco or any sort of octane booster?

 

Consensus is - doesn't work. The octane change produced by one can of additive is very small.