So I just picked up a pair of coils and installed them. Stance AL+ with 12/9s. Everything bolted on with no problem. Got about 2" drop all around. Camber looks to be roughly 2 degrees on rear and barely noticeable on front. Rolled around the block a few times re-measured height and re-checked all connections. Everything is still tight and no noticeable height changes. As I'm driving home from the shop I immediately start hearing a "clunking" noise from the rear passenger side coil. When I got home I rechecked all connections and everything is tight. I also adjusted the dampener effects from lowest to 8 out of 15 and still made no difference.

At first it sounded as if the upper mounting plate was loose and it was clunking against the chassis. After I carefully continued listening you can hear an almost faint "boing" noise at the same time almost as if the spring seats where loose allowing the spring to almost bounce on rebound.

I re-tightened the tension on the spring and the noise still happens. Yesterday I took it back to the shop and swapped the rear sides and loosened the spring seats back to match the same spring tension and ride height of the other rear. The noise followed to the driver side rear, so we know that its the particular coil for sure. We have yet to get it up on the alignment machine or ramps to see if it's hitting anything but after taking it off and swapping sides it looks as though it's still brand new, no scrapes/dents/marks or anything.

Is it possible the dampener is defective? Any other ideas?