I believe the US late war high octane avgas was 115/145. 100/130 was indeed widely available more or less the entire war.
I think the British had something they called "150 octane", but I'm not sure that really was "better" or even different than the US 115/145, or was it different testing protocols etc.
Interesting, especially the 115/145. The octane equivalent #s from that era seem to be all over the map.
If actually 115/145, that's a big delta in performance for lean operation, and certainly helps the narrative. Do you have a primary source? I'd like to read further.
Regardless, what's certain is the Germans were in the high 40s mmHg for manifold pressure in late variant DB 605, vs the Allies were in the 60s mmHg for Merlins.
I believe the US late war high octane avgas was 115/145. 100/130 was indeed widely available more or less the entire war.
I think the British had something they called "150 octane", but I'm not sure that really was "better" or even different than the US 115/145, or was it different testing protocols etc.