Not sure of a cheap oem CDI. Stadium Yamaha has excellent reviews around as an oem parts supplier and 10% below MSRP! If you're going that route, you may as well just get a re-programmed CDI. Suitai is the oem manufacturer of Kymco CDI's. Zombie has purchased through them directly. There are many posts on here about them. Honestly, I would just cut the one you have. If you somehow manage to mess it up, the worst that could happen is you need to buy a new one anyways!
As for the carb, there is no reason to change the settings with the stock set-up. You would just be running too rich! The point of up-jetting is to accommodate the added air the K&N filter provides. If you look at my avatar, that is a pic of my carb with a K&N filter attached.