Jesse try getting a guy who knows about cars to call up (or do it yourself) and then see the response... I guarantee they change their tune when a guy with not much time to spare is on the other end of the phone
About the car serial numbers, their ordering system requires that field to be entered before they can process the order, Nissan JP do it too. My mate Ikeda just gives them a chassis number from a car they're working on (if it's the same model) and HKS are happy thereafter... it's stupid I know.