A six point roll bar with additional chassis stiffening braces. Barely visible are the chassis stiffening braces that connect the rear shock mount to the roll hoop common with the door diagonals (not the NHRA required upper hoop braces from the same rear shock mounts to the top of the roll bar). Measurements showed 120% increase in chassis torsional stiffness (from 6,100 to 13,500 ft-lb/deg).
The weight of the standard NHRA required tubes:
51.30 lbs (using 4130 steel tubing)
Weight of additional stiffening tubes:
15.64 lbs (using .035 in. wall 4130 tubing)
Note also that no signifiant increase in stiffness occured by installing just the roll hoop, door diagonals, seat belt bar, and hoop top braces.
(i.e. just the basic roll bar)