I don't really know a lot on this subject but once I saw recommended for KW coilovers to leave things loose, drive slowly around the parking lot, and then tighten things down. I can't remember the specifics but apparently on the 300's a lot of people had problems getting them correctly tightened so they were quiet. Just an idea, loosen things up drive some and then tighten them down with the weight of the car holding them in place.

Les