That is the focal point of force and is going to be where the "cage" gets pushed through the roof of the car as it deforms dueing the impact. I hope he builds his own power plant (based on what I see) so we don't have to worry about him going to fast!!!
I wouldn't worry about him going too fast. He just added about 300 ounds to his car! You would think after all of that welding, he would have improved a little by the end.