i usually avergae 250-260 per 10-10.5 gallons. I've never noticed any difference in power when switiching to 92 octane, except that my bank account clears out pretty fast, lol.
I have a really stubborn and mislead friend( he once told me blow off valves are available for Naturally Aspirated engines and that he can get a 'mod chip' for his pos chev cobalt and that it'll add a rediculous amount of hp for under 100$) and he has told me also that running your car on 92 octane was better for your car, and it keeps its running better for a much longer time and all this other crap... when i spoke to other people about the running on 92 octane, they all said that if you're not forced induction, or have a big block v8/10/12/ w16 etc, youre burning the fuel up faster and that there was no significant difference in performance

 

our cars are capable to run 87 because of the computer being able to change the timing. it doesnt necessarily mean its the best. thats why i run 89 octane. as far as running 92 thats just silly. there might be a slight hp gain at 89 but not any higher. i only have a CAI and exhaust, but i had white build up on the spark plugs which means its running lean. the compression ratio is boarder line on having to run on 89 anyways which is usually 10:1. and ours are 9.5:1