Kits don’t include jets and metering rods, those are the hard to find and expensive parts. Also when you buy a rebuilder, you don’t know what you are getting. If your phenolic resin fuel body is warped or damaged, your screwed. That’s why its best to buy from a reputable rebuilder that specializes in thermoquads, guaranteed working carb out of the box. If you think you can buy a core and DIY, you are rolling the dice and may find yourself down the rabbit hole.