Re: A couple points ...
"Octane doesn't do what you think it does"
Increased octane simply cause the fuel/air mixture to yield a faster and more controlled burn, which is necessary in high performance engines to achieve tighter intake/compression/combustion/exhaust cycles - therefore maximising power per combustion and also improving the ability of the engine to achieve more complete combustions in shorter time - therefore power through into higher rpms.
A low performance engine won't notice high octane fuel, in fact may even perform worse. A high performance engine conversely will be held back by low octane fuel.
I used to notice a dramatic difference between 'normal' 97 octane petrol and Shell 'super unleaded' (98 octane) in my 750cc motorcycle, which was a fairly high performance spec engine. Especially on a cold day when the higher octane fuel combine with nice cold dense air yielded heaps of extra power.
I know a BP garage on the A406 (north circular road) in North London, which has a single pump which dispenses 102 octane unleaded. I never got to try it out in the bike, as it was always sold out when I visited... shame!