depending on the size of your track a 13.5 is probably plenty.
Allowing lower turn motors makes the trucks hard to control for newer drivers and they will loose interest quickly if they are breaking parts and wrenching all of the time.
If you are a good driver, you should welcom the fact that your local facility is trying to keep things a level playing field and keep the new guys interested. You should be competitive with any power source if you are good.