That has some good information, but there are many companies out there that have good full bodies. You will run into good and bad about every company out there. I can tell you thisD2 and K-Sport has several different levels of coil overs, and yes the rumor that D2 and K-sport are made in the same place. Personally I do not know many people that run Function Forms on the track or found anyone that has. I researched for over a year and decided to go with skunk2 a company that has multiple weekend warriors that are full out track prepped cars, But so does K-sport. There are many knock off coil overs out on the market right now. Many people run the buddy clubs on and off the track. Here is a link that might help:
http://dwsparts.rpmware.com/suspension/ ... &cid=10110
This website took over springrates.com which as a great place to find all sorts of suspension parts.
Now I can personally tell you that the Skunk2 Pro-C coil overs are extremely nice. They only have 12 settings instead of the 36 but each click you can really tell a difference. I got my car done and took it around the first clover turn on the high way on the softest level and then turned it up slowly and i could push the car harder and harder each time.
I keep up with all sorts suspension stuff pm me if you have any questions. Check my build page and that might give you a idea on some other things too.