Do you have the lastest rule book? There was a change made to gussets;
"Gussets are required at tube junctions of hoops and shoulder rail. Gussets shall either be made of plate, tubing or fabricated from sheet. Plate gussets shall be made from mild steel, .125 in. minimum thickness and 4 in. per side, preferably stitch welded on the outside of the tube junction. Tube gussets shall be a minimum of 1 in. O.D., round steel tubing with a minimum .120 in. nominal wall thickness although it is recommended that tube gussets be of the same O.D. and wall thickness as the main roll cage material. Tube gussets shall be constructed such that the outside edge of the tube gusset be at least 4 in. from the tube junction point, see Figure 3. Gussets are required at all shoulder bar attachment points. Grinding of welds is NOT permitted, see Figure 2. Gussets may not be used as aerodynamic aids and shall not exceed 6 in. in length without prior technical review and board approval."
Could be wrong but I think Nathan put in for this rule change, in my opinion I think it was needed.
Mike