I just found this after it was put to my attention and I am still doing some more research about it.
"dentsport02-07-2007, 08:01 PM
There are a lot of intricacies in choosing the right cage. For one, the Safety (I don't think you meant Stand, they make suits) 21 is a steel version of the Cusco which is Cr-mo. The Safety 21 cage has only 2mm of wall thickness. Just because the cage is used in some time attack car doesn't make it safe. The standards in Japan are very relaxed. The bends on the two brands are identical. The cages are both NOT legal for SCCA, NASA, RALLY AMERICA, and most time trial clubs because they lack:
Diagonal bar on main hoop
A pillar bars are bent around dash making them into a crush zone
The tubing is 1.5" which is too small in diameter for cars over 3000lbs by popular rules.
Things get more confusing when considering a true competition cage. By anyone's standard the FIA spec cage is the epitome of safety and design. Well, not by SCCA's new standard. The SCCA has told us directly that they might not sign off an FIA cage for road racing as the door bars may not be legal, add to that T45 (the UK cr-mo equivalent) isn't recognized or automatically approved by SCCA standards. (this conversation pertained to road racing) we have had no issues and heard of none with FIA cages and Rally America.
What you'll need to have is a 1.75" main hoop, diagonal bar and harness bars and most likely 1.75" diameter on the rest of the cage with a .120 wall thickness made from DOM tubing. That's Drawn over Mandrel. That and having the local tech steward come inspect your design layout and then inspect during the build process to make sure that you're not running astray.
T2 rules are more complicated for SCCA than other classes as the new NASCAR door bars are being mandated, but not according to every steward I've talked to. They won't approve t45 here in New England even if it's FIA approved.
I have a custom cages FIA cage that isn't FIA anymore because I changed the design a little bit on my own knowing that I wouldn't need to fall back on FIA standards to get me through tech.
Dent Sport Garage