I have spent a decent amount of time researching this. Do any of the major road racing sanctioning bodies have any restrictions to removing unibody structure when installing a cage? I want to maximize room in the passenger compartment with say, a 6-point cage. One way I have thought to do that is by cutting just enough material from the unibody right behind the side windows and roof so the main hoop of the cage can set into the unibody structure as much as possible. I would then weld the remaining unibody structure to the main hoop. Would this be legal? Does the main hoop have to be exactly vertical or can it be tilted just a little bit?