Zev,
I would suggest you buy a bunch of rear sprockets. Since you are new to the kart, you will want to change to shorter/longer gears for each track and see the results. Your personal style might prefer different gears from everyone else.
I’ve got a guy who makes sprockets and I can get them for wholesale at $12/ea. If you are interested, I am placing an order this week and we could order together to save on shipping. :idn: