Originally Posted by thorongil
On the fronts, there's a rubber insulator/isolator that fits between the top of the springs and the upper spring perch. The gray pieces of plastic that are pictured on the springs are to protect the coating on the "dead" spring coils (the coils that touch when the car is under static load). While I don't have experiential knowledge of the Cobb springs, from what you describe it could be quite possible that the springs are not seated properly. It might be possible to lift up the front end to unload the springs so that you can rotate them and seat them properly.
Also, did you orient the upper spring perch properly? I know for the 02-07 front struts, there were three holes in the upper spring perch that needed to be pointed outward (or, in the same direction as the lower strut clevis/bracket.
Lastly, did you torque down the upper strut nut properly? If that's loose, the hole thing will rattle over bumps.
When I installed the springs I did note how the upper perch was oriented and replace it the same way. My first fear WAS that I hadn't torqued the top nut down properly but I checked it and it's down as much as it can be. I did make sure that the top insulator was in place before I put it all together as well. As soon as I can I'm going to try and make sure everything's seated properly. Thanks for the help.