I'm very familiar with octane boosters as a result of racing highly tuned two-strokes.
Silkolene's pro-boost was a permanent addition to my toolkit.
However,that was only required as a result of skimming the heads and increasing the compression ratio.
It avoided detonation,that's all.
In my opinion,any claims of increased performance,just because of higher octane fuel (and no other mods) should be taken with a massive pinch of salt.
A 'placebo effect' is possible I suppose,in that if you expect to feel a difference,you will.
I've also seen tests in motorbike magazines of things that you drop in your fuel and they claim more power and increased efficiency.
The tests revealed little/no difference.
I seem to remember the biggest measured difference,in engines that produce over 160bhp/litre (far higher state of tune than most cars) was under 1 bhp,which they said could have been down to a change in atmospheric pressure as much as anything else.