I love to read explanations like Don's and Bob's because it is obvious that they know their facts. Without getting into detail, it is my understanding that running any higher octane than is necessary to prevent "ping" or pre-ignition knock adds no improvement in power or efficiency, and in fact may be slightly less efficient as the engine is operating at/near peak on lower octane, faster burn. I would expect that at the higher altitudes CJP was getting some amount of ping/clatter at WOT, like climbing in the mountains, and that the higher octane fuel reduced or eliminated that ping. If this is the case then the higher octane fuel is good for the mountains, but may not be necessary if he visits the coast of CA, other than the time the ECU may take to re-learn the ambient parameters.
Am I off base here?