11:1 too high for pump gas?

I was talking to a fellow whose brother has a 900HP mustang running E85. I didn't get into detail about what compression he is running .. I wished I asked... but the car is EFI. I know it's doable but was interested in the pros and cons of E85.

I would like to hear the way you make more HP with low octane rather than race fuel... or is it top secret?:D
I didn't say I could make more horsepower with low octane than race fuel. I can make more power with race fuel (or E85). I said I could make more horsepower with 91 octane than most people could make with race fuel.

As to the E85. I didn't like having to run everything out of stainless steel or anodizing every aluminum piece that was coming in contact with the ethanol. I had carburetor internals that were getting a white powder all inside them and I had to flush the fuel system with gasoline after every use. I also had to make my own E85, as none is available in this mountain valley.