Its not dangerous, but you won't really see any advantages from it. You're just throwing money away.
Now if your car is tuned the tuner can advance the timing to take advantage of higher octane.
But if you do that, then you have to run high octane all the time. Its up to the owner of the car.
it's debatable, but why bother with the risk. People have told me that regularly running higher octane (on a 87 vehicle) can lead to problems and others say its fine. It's all about energy density, a higher octane will not add more oxygen or hydrocarbon. In short no more power, the only power is from a higher compression that requires higher octane.
thanks for all the info, i didnt expect much of an advantage. When i first got the car added fuel cleaner and then the next time would be octane booster. and i could feel better throttle response but that was it. I'm looking for a tune! hehe $2.50 a gal i cna afford it YEAH!