I have EZ-GO and not familiar with your CC, but as far as I know, there are no easy performance enhancements for these carts and no one makes performance parts. I think liability with these things is huge. The governor trick is about it, and it will eventually eat up your cam followers from valve float. Mine did. You could put heavier springs in. I didn't waste my time looking at this as it isn't going to buy you much. You could mill the head and deck the block for more compression, but then you need to build an adjustable cam gear to bring the cam timing back in.
For an EZ-GO, the best solution is a larger 350cc bottom end topped with the 300cc head. Maybe something like this is possible with the CC?
Just throw a 600cc bike motor in it and be done. Dry nitrous shot?
Show us what you end up doing. I'd like to see it!