[1BAD89]

If your stock, always run what the manufature recommends! As far as your bike, if it says run 91+, you better run 91+! If it is a newer street bike, it'll run like **** with 87 in it, and you could have possible engine damage. I just don't understand, even if you decided to use 87, the current crop of streetbikes get like 40mpg, why use 87, you'll be saving maybe $.50 each fill up, and it's BAD FOR IT!! I'm assuming a street bike?? Different motors are set-up to run on different octane ratings. If the manufacture recommends 87, and you don't bump the timing or anything, your wasting your cash on anything higher than 87. Chevy says only premium fuel in my 2000 SS, if I use 87 octane, I will be rewarded with " knock retard" by the computer to compensate for the lower octane, and I would probaly lose around 20 hp, because the computer sets itself up in kinda like a "safe mode."

i read once in muscle mustangs and fast fords an article where they were dynoing modded mustangs to see diff hp changes and they made a point to say that they had run 94 octane for all the runs

Mod'ed is the keyword there.