What type of roll cage can i have in my car that is legal?

A roll cage, will be illegal, as cars are not ment for racing, unless you motify them. In many parts of the country there are laws, now, that you can not modify or change a cars demensions, as any change has to be engineered by the company or a certified mechanical engineer. So the days of building street rods are over, as noise and polution, now have the last Word