Title speaks for itself really.
I think adding a slight speed boost when you successfully do a 100+ score trick combo, possibly scaling with the score of the combo (up to a cap?) would be a good addition.
Especially in races, slowing yourself down to perform tricks and grinding just to gain an overkill amount of energy just doesn't feel good. Also, in addition to the speed boost, you could implement a system where the speed boost gets stronger or weaker when used in a race depending on how many checkpoints you have compared to the other racers, thus adding some kind of recovery mechanic, which i feel the game could really use.