The only thing gasoline with too much octane will do for your vehicle is make it less efficient. SOME of the high octane has a lot of additives in it that will create excessive deposits when they are not burned.
Older vehicles can be ajusted so that they perform better and are more efficient with more octane, but it takes serious tuning to make the most of it, and the gains aren't worth it unless you just like to fool with it.
Newer vehicles will sometimes adjust to the high octane gas by SLIGHTLY leaning the mixture and increasing the timing. However, they are designed to require less octane with the same compression ratio and timing as older vehicles.
Increased timing lead actually creates NEGATIVE torque, by firing earlier in the stroke, before the piston reaches TDC, actually trying to force it down. It does increase cylinder pressure though, making it more efficient. But even more efficiency can be had by increasing the copmression ratio to gain cylinder pressure, and decreasing timing lead. You get the same cylinder pressure, with no negative torque. That's why you see increased compression ratios these days.
