HKS said it correctly, higher octane fuel actually burns more slowly, resulting in less energy output for a given volume. So, if you put 92+ octane fuel in a car that says to use a minimum of 87 octane, all you are doing is paying more for the gas and getting fractionally lower performance and mileage.
Cars which actually require the higher octane can negate the lower energy density of high octane fuel and obtain more power for a given displacement through the use of higher static compression and advanced ignition timing.
And for God's sake wje, try to compose a thought before you open that windy hole in your face. This statement qualifies you as the most gullible person on AT
I can tell you've never listened to Pat Goss on the radio. Yes, harm can be done. Your car's computer may be expecting 87 octane gasoline, but then 90+ octane gas is applied, tricks start to be played with your computer and a lot of things get thrown off. This is quite simple - use ONLY the recommended level of octane for your vehicle as stated in your owner's manual. Using anything other than what's recommended could lead to other problems down the road.
Your car's computer has absolutely no idea of what octane fuel is in the tank. The only thing your car's computer can do regarding octane number is detect detonation and adjust the ignition timing and injector pulse width accordingly. Apparently you and Pat Goss are "tricked" much like your car's computer.