They tested all these fuels on a Subaru, and the Optimax (as it was a while back) increased the BHP by 40

over stock unleaded. All tests carried out under the same conditions, on a rolling road.
Unfortunately, on a N A engine the gains are less, probably in the 2 - 5 BHP?
HOWEVER, the big advantage is that these high Octane fuels are less prone to 'Pinking' and they don't burn as hot as normal unleaded, so this is good for the engine. Throttle response is better and the care will feel more lively.
I used to run my Honda VTEC on Optimax every time, but that was imported from Japan so was used to running on 100 Octane, so I just wanted to keep it that way.