It's been 10 years since I worked at engine calibration at Jaguar, but I do remember the production tune we made was able to work in a wider operating area dependend on fuel rating/quality both upwards and downwards.

Active Ignition Timing
A nice write up of the principle used by others.

i'm curious could you run a 100octane? There is a local 76gas station that sells them.

Waste of money, unless you're running a tuned engine with enough compression/FI.