Myself.. the bar under the bottom isnt helping the force that bends the rear end.. the bending force is forward so I had more beef on the rear of the housing all the way out.. I do add a tube from the shock mount to shock mount and attach to the bottom of the housing
He has a bar on the bottom and back of the rear. I am sure it helps, don't think it's necessary but he obviously did.
Brett Miller W9 cnc'd heads STR Chassis fabraction