I was wondering for the Go Kart competition if the track needed to be high for a good prestige,
Prestige seems to be a combination of 3 things: the ride's excitement rating, the ride's duration, and the ride's scenery.
Altitude of the track above the ground surface has a very, very slight effect on excitement (like 0.01 per meter). You can see this if you plunk down a blueprint ride, test it, then use advanced move to change its height very slightly, and test again.
So to answer your question, yes, the height of the track does have an effect on prestige. But it's very tiny. It's an itty bitty fraction of excitement, and excitement is a fraction of prestige. So in general, I wouldn't worry about this.