[JKnight]

I run 220 lb/sq in. Hyperco composite leafs on my car with a Fays2 Watt's link. I can tell you that the ride is great due to the lower unsprung weight and it handles really well. I haven't done any competitions so I have no numbers or rankings in events to back it up, but for less than $1,500 I feel I have a very competent rear suspension. I believe I will need to add a sway bar or more front tire to improve balance at some point, but for an 90% street car it's not really necessary. I would have preferred the adjustability of a 4-link, but given my budget it just wasn't in the cards.

I would think one of the limitations, downsides, for any fiberglass spring is going to be with axle wrap/wheel hop. This has not been an issue for me thus far, but I'm only running 425-450 hp and have a heavy 9" rear end in the back.