Besides the obvious (tires, emissions), what are the changes along the path of street car to track car that make a vehicle no longer legal to drive on the road? I’m in Oklahoma, so there are no state inspections or emissions testing to deal with. And I get that stiffer suspension and competition brake pads would make street driving super obnoxious, but I’m most interested in what’s legal.

Roll cage w/ no helmet seems like it’s clearly a bad idea, if not illegal.

If you were modifying a car for semi-regular track work (lapping, not real racing) and occasional (maybe once or twice a week) street & back road driving, how would you set it up?