I'm not sure if the head stay will work, it may, you'll have to bend the tank up a bit to clear the plug, maybe one of the newer shortie plugs will give enough clearance. The swingarm does need to be narrowed, the rear motor mount will need to be bored to 17mm. The carb would work as a 38mm, but I'd bore it to a 40mm. not sure how the 03 airboot will line up, if it doesn't use the 99-02 air boot, it will bolt right up to your 03 cage plate,it works good. Using the CR pipe, you'll have to change the end that goes into the cylinder, cr goes over, kx goes in, pipe mounts and modded around the water fitting for clearance. don't know about the 03 but you can make the 02 hybrid in a weekend pretty easily.