i dont know about 2 strokes or stock saws but i race "stock" type class 4x4 trucks. alot of guys think there is a hp gain in using race fuel in a stock motor, but it will really hurt a lower compression motor. (burns to slow) they think race fuel is like some kind of rocket fuel i guess.
octane numbers are the fuels resistance to detonation ( pre ignition). so if you dont need the high octane why pay for it???
i run a 10.8-1 CR, 550 horse, mopar 446, with 37 degrees of timing and locked dist., on pump 93 from amoco. no problems.