I guess I'm wondering if there is an official rule on this or if it is a judgment call. Couple scenerios come to mind. Let's say you have a current 8.50 cage and you want to convert your door bars to swing out bars, which are allowed. Do you need to get a re-certification or are you o.k. Or you have a current 7.50 chassis and you have a shop enlarge the funny car cage for more room, following the book. Would you need a re-cert in that case?