Since this is a Unitbody car, the main hoop does not need to connect to the frame or frame connectors. Because of this, there are only two points where the main hoop connects to the car using 6-inch by 6-inch x 0.125-inch steel plates that are welded to the floor. Full frame cars usually use four points that include two that angle inward slightly to connect to the frame. Add that to the two rear braces and two door bars, and you have an eight-point roll bar. You can also bolt the bar down by sandwiching the floor between two plates. The wood is there so the bar can be dropped down and fully welded while in the car.