Can I just go put 100 octane gas in my car? If I am going to the racetrack?

I live next to a long large hill which I drive up with a truck and camper. When I use 87 I can't get past 45-47mph, when I use high octane I can hit 53 no problem and get better mileage. They say it doesn't buy you anything unless tuned for it, but I proved that wrong. Also I had a cheater pipe(catalic converter replaced with straight pipe) and gained at least another 5hp and was able to use Mexican gas without problem. Before that Mex gas would make it ping and hesitate(where there is no gas stations in Mex you buy it from people on the side of the road and you don't know what youre getting). Hope you have a good time and good luck