That noise is not coming from the springs. I assure you, that is not it. I am not sure what it is, but you gotta keep digging. I'd suggest you raise the car to see if the noise goes away. Also is the noise front and back? I can tell you right now there is no way on this planet I assembled 4 bad dampers, when I have yet to even have a blown damper in 5 years. So don't jump to assumptions just like the last guy that accused our dampers of being defective which was on a 350z. This customers gf made a huge deal on another forum accusing me of making her a defective product. After months and months of telling her that it was not defective, and even inspecting them for her for free I finally just told her to bring it to my shop. In less than 10 minutes not only did I find the noise, but it had nothing to do with the coilovers. Guess what, they brought another 350z with them that had another noise. I happen to make both sets that same week. Guess what I found out in less than 5 minutes...the freaking swaybar bracket was complete gone for the rear swaybar. That was causing the noise!! Whoever installed them did not know what they were doing..and I got the short end of the stick cause she ended up making a thread complaining about it.
http://my350z.com/forum/north-west/450472-amr-coilovers-2.html
Well you will see she apologized publicly for blaming my company for something that was not our problem. You see how easy things can get out of control especially when people have no idea what the facts are or what is going on. This person made a entire thread to make us look bad to only apologize later after I told her the truth and the facts right from the very start. In the end I ended up fixing a problem that had nothing to do with our product, but a poor poor installation.
So don't jump to assuptions. It could be anything. I have no problem inspecting the coilovers for you, but I'll tell you right now I highly doubt they are the problem. If I happen to see there is a defect I will ofcourse fix it free of charge. But it is very unlikely..and I would hate for you to have the downtime for me to just say they are okay. So make sure to double check everything, and try to track it down before we go that route. Good luck!