i can run 91 no problem in it. the factory compression on the '02 camaro and firebird's, for example, with the LS1, had 11:1 compression from the factory. those cars ran on 91 or higher octane per the owner's manual requirements. most cars these days have higher compression but still can run on pump gas (91 or higher). most people don't read the owner's manual when they buy a new car and just fill it up with 87 and then complain of "engine noise" at the dealer. take the Mini coopers or the little Smart cars for example- they require you put 91 or higher in them due to high compression.