I know this has been covered before but I had a friend telling me that he is making more horsepower and getting better mileage by running 87 octane in his stock 02GT. I was wondering if anyone could explain this to me. I have ran 93 in mine since it rolled off the showroom floor. Am I hurting it? or just wasting my money since the timming is set so low from the factory? please any info would be nice.