During the past couple years I've been designing, testing, and producing various parts for 2nd gens including reinforcements for sub frames and use with the PTFB G-braces. I've been selling them to members on the various forums and decided earlier this year to form a company called Laboratory Fourteen "Lab-14".
While folks have used various triangulation braces to the upper cowl on the street for many years without any noticeable detrimental effects to the cowl there have been people who use their cars for auto sports who have experienced damage from constant flexing and the shear forces.
The pinch welded sheet metal where they attach at the top of the firewall flexes pretty easily and you can literally bend it with your hands if you grab the ledge and apply pressure like you are trying to break a pencil with your thumbs. I've tested several configurations for cowl support in conjunction with the use of the PTFB Pro G-braces.
Trey, Doug has a bunch of my products and will probably show them in his project thread here when he gets to it.
Shown below in the first pic is the kit I sell for upper cowl reinforcement when installing Pro G-Braces without any other upper lateral triangulation. The larger plates sandwich the pinch weld ledge on the drivers side and narrower ones on the passengers. The different sizes are necessary because of the recess for the wiper motor which allows more leverage for the G-Brace to flex that area. The reason the plates are wide is because the G-Braces mount almost centered on the large openings on the top of the cowl which allows more flex of the vertical part of the firewall. With the wide plates forces are spread out to the horizontal sheet metal on the top of the cowl.
I also have upper and lower control arm mount reinforcements, UCA mounting studs by ARP, sway bar mounts, and adjustable UCA mounting stud supports as well as various other structural reinforcements for both the early and later style stock 2nd gen sub frames.
The lower pics were taken during sub frame deflection testing of various combinations of Pro G-Braces and reinforcements.
