You will likely have to move the crossbar forward. This used to be a good thread until photobucket killed the pics:

http://www.pro-touring.com/threads/7...ars-no-shakers

Don

Do you mean: from the point above my head where the rear brace meets the main hoop to where the passenger side brace meets the trunk floor? I have thought about it.

From driver's side main hoop just behind the driver's head, to the passenger floor where the main hoop is welded or bolted to the floor. It keeps the main hoop from deforming to the side and is usually required for any track use. It makes it hard to get into the back seat area, but can be made a bolt-in to make it easier to work back there doing upholstery or whatever.
A diagonal on the rear supports will help in torsion but not do much for safety.

They are a good start, but I think they need more bracing to be very effective.

I already have a removable cross bar on the main hoop.