They require a rollbar at Willow Springs Raceway on convertibles. I try to go on the Thursdays before Spring Fling, because there's a great group of Mopar guys there and it's a lot of fun.
I bought a kit from Summit and welded it in. It had extra tubes to make a 6-point bar, but I didn't want to be climbing over the bars to get in and out of the car. I also didn't want to cut up the car to put it in, so I fitted it between the rear seat back and bottom. It's tied into my sub-frame connectors and has the metal plates welded to the floor. The back seat is still useable by adult sized folks.
