That's not entirely true. In fact, it's more false than true. Lower octane burns faster and hotter while higher octane is less prone to detonation. Less prone to detonation because it's more stable and burns slower. As a result, less power is produced by the same volume. A good rule is to always run the lowest octane that you can get away with running. Some of you sea level guys may have a different philosophy, but it works just fine up here.