I don't think it would be a brace to the frame because the lower quarter panel would be in the way.Do you see that round bolt on the very bottom of the bumper? That's the hole that I was curious about.It is to the right and below the last bumper bolt.   Yes,my car has those corner pieces on top of the bumper,also bumper guards that bolt on where the two rear bolts are located.There is also a cross piece between the bumper guards,on both the rear and front bumpers.