[Homeslice]

You have to adjust timing to work with the fuel. If you do not do this (or you dont have knock sensors doing it for you), then using higher octane is useless, unless maybe you've got deposits that are causing pinging (premature detonation)

End story: If your ride specifies premium, you will most likely lose power if you don't use it......duh. However, if it specifies regular, then you're wasting your time using premium unless you 1) have modified the engine somehow, or 2) you're trying to reduce pinging (and in that case it would make more sense to clean your intake valves & combustion chambers instead)