I disagree with b210sleeper, and agree with 1200gxman on most, but not even at 11:1 do you really need high octane, the 20V blacktop 4AGE motors run 93 and/or 95 happily, and they are 11:1 standard.

Clive, I used to run my 4AGE that's turboed on 95 just to make sure, but sometimes they ran out and I used 93 and it made no difference, no pinging at all.

Octane can help prevent knock, but if you fuel your engine properly with the right timing settings, you don't need such a high octane number most of the times. Some engines are also less prone to knock than other, due to combustion chamber, piston and valve design, and with them you would be able to use far lower octane and run more timing than most others.