I've heard some raves and further discussion of these recently. Obviously there is a huge weight savings. But what else is there to these? I'd like to improve the handling of the rear in the off season and would consider this as a potential improvement to get the ultra stiff 5 leafs out of there.

 

I've heard good and bad... They're popular with some of the Super-Stock drag guys, but there have been a couple of street guys who had problems. It's recommended to wrap or tape them on street cars, as rock chips CAN cause them to start splintering. In addition, there are some concerns with stiff bushings and side-loading causing undue side-stress in a "cornering" environment. I believe that the springs are actually composite - aluminum ends, bonded to a fiberglass "leaf".

Here's one that had problems - you might also do a search on that website for "fiberglass" in both the Mustang and Ford Racing sections - I've seen more there about them than any other site. Sounds like ~$435/pair in cost...