I don't think any of the small cans of octane booster you can buy at the auto parts store increase octane by more than about one tenth of a point (i.e., from 93 octane to 93.1 octane) when added to 15-20 gallons of gas. To see any measurable or noticeable change in octane, I purchased an additive that was sold in a roughly ten gallon container and delivered by freight. As best I recall, mixing it with 93 octane in a 9:1 (gas:additive) ratio increased the octane about seven or eight points to 100 octane. ... It's been a few years so I won't argue if someone comes forth with more accurate information.
PS: I think it was something like this:
Hitrate