Best guide or any starting point on making a roll cage for. A 6 pt harness. Trd cup started here in socal, hosted by extremespeed. At willow springs etc. im planning on participating, but i wanted to get a roll cage ahead of time. Advice?

Start by finding out the regulations for the events you are taking part in, they should list things like material type, tube thickness etc etc. Once you have that it should guide you to the best type of cage to buy.

A local fabricator with extensive cage fabricating experience will be your best friend. But like Nial said, look up regs for the event so you can atleast go into fabrication knowing what the car needs and they dont make you a cage thats below spec for the event you are doing but in spec for drift or something else