I think I understand all the frame mods, except the ones in front of the engine. What purpose do those mods have?When we were installing the roll cage in the Pontiac we read on the rules a bit.
In section 4:10 Roll Bar it says...
"All vehicles with OEM frame must have roll bar bolted or welded to frame"
Another important detail is...
"Unless an OEM framerail is located below and outside of drivers legs (i.e., 55 Chevy, '65 Corvette, etc.) a rocker or sill bar minimum 1 5/8" X .083 CM or .118 MS or 2" x 2" X .058" CM or MS Rectangular is manditory in any car with a modified floor or rocker box within the roll cage uprights excluding 6 sq. ft. of transmission maintenance opening).
In our case we ran outriggers off the frame and put a length of square tubing in the rocker panel.
When the NHRA inspector came, that was one of the first things he looked for. The cage was certified with no problems.
Here are a few pictures of the Pontiac roll cage.
BTW, nice damn work!