Fortune Auto coilovers are some of the best coilovers you can buy. They're hand built to order, and use high quality AmsOil shock oil/components. They are also built to the spring rates you specify when you order. I recently Installed and have been testing a set of 510's w/ 8kF 6kR on my friend's DA for about two months now and I can tell you they are phenomenal. If you're only street driving I'd recommend the 500 series. The 510's have more aggressive valving dynamics and drop travel is less than that of the 500s; they're mostly for track use. Oh, you also get shock dynos of each one of your coilovers when you order.
If you want more proof go investigate their website. They have contingency programs with most of the major racing organizations in America.