Yah - anyway, back to the guy's original question.
If you read your manual, it recommends 87 octane.
I have used just that for 42,000+ miles, and my car still purrs like a kitten.
Using anything more than that is a waste of money.
I will patiently wait for the flames from all the 91+ octane freaks out there - but all you have to do is PROVE it's better - and not by how it "feels". Real proof.
All you are actually doing by using high octane gas is hurting your performance and increasing your the deposits in the combustion chambers. We can't effectively use it, so there's no reason to buy it.
Stick with the 87 and the extra few bucks in your wallet.
~HH