I think opne material arms are well within the philosophy, but think that there must be limits on the geometry adjustments. the mounts are fixed, that is a given and I think a good place to keep STL. I would allow IT-type slotting and reinforcement for strut towers, and some reinforcement for STL upper arm mounting points. lower are currently allowed 6" radius of reinforcement.

to keep costs down to some degree, maintaining stock arm critical dimensions on at least ONE arm in an SLA setup, and on the lower arm OR shock tower (camber plate) in a strut setup is completely acceptable. audi/VW's quattro 4 ball suspensions as well as the mitsu/chrystler/kia/hyundai 3 ball knockoffs all count upper or lower arm or arm pairs for this purpose. hybrids, like the toyota super strut etc... should be judged as SLA. rear beams, multiblades, 5 link types etc... will need a better rule than I can come up with at 11:30 pm.