shut up chuck, heheh u dont want none of this hduce...well what i mean is that okay i've tried ONLY once using 87 octane...and man did my car run shitty!...i think if the car recommends 91 then use it...i doubht you'll see any gains with 91 if it isnt high compression, the graph that is shown is probably a car with high compression engine and good mods..but either way if it recommends it, use it....