The above says it all. If there's no benefit to higher octane, why pay the difference!!! Sorry but I don't put a lot of credibility in seat of the pants assessment. Put it in a dyno or run a quarter mile.

Another thing to keep in mind - did you know that the higher the octane, the less flammable the gas becomes? Pinging is another term for detonation. If a car pings or detonates on an 87 grade but did not on a 91 grade, what does that tell you? Therefore, you do not want to put a fuel in your tank that would tend to hamper combustion due to its flamability characteristics. Use what the owner's manual recommends.

In fact, one of the tricks in passing a smog check for an older vehicle is to use a regular unleaded fuel even if the car calls for premium. Since the fuel is "more flammable", you burn more of it in a combustion cycle and exhaust less unburned gasoline which means lower HC emissions.

 

I know that some octane boosters contain lead in them which can cause damage your catalytic converter. So when you need to get a smog check, your car might not pass. Just my 2 cents.