Finally, there is one piece of the subframe exposed – underneath the car. Because the rear cross pieces installed and hidden in the box sections behind the seats must stop at the driveshaft tunnel, we complete that crossbar by adding a piece of the same tubing under the floor below them instead of the stock tie plate. This is stronger, completes the crossbar, and is welded directly to the main floor runners which are another main structural member of the monocoque. I also like it because it adds about an inche of clearance over the stock tie plate for larger and more aggresive exhaust systems.