i installed few coilovers to lots of different car and noticed few knocking noice like that.
double check all your bolts and nuts, some of the coilovers i installed bottom piece where it bolts on to LCA was little bigger then the original parts. i tightened it all the way down but it was making noise so we checked again and i see little gab in between parts. i had to tighten it again hard and the noise was gone

 

yeah...it's been a few years since these were installed... i thought of having them completely taken out and reinstalled all over again... but the thing that bothers me is im not the only one with an SC who has had this issue after installing the Tein FLEX... all other coils seem to be no issue...

 

i have the same problem with mine after i installed the tein ss coilovers myself. i know for a fact that the upper nut is tight, it was making that clunking noise even before installed the tein's. it just sounds louder now on the front right so im thinking whatever i did to install the coilovers made the knocking worse.

I have a feeling its more the bushings than the coilovers.

 

make sure your sway bar nuts are tight. you have to hold them with a wrench or pliers and tighten the nut. that's if you removed your sway bar end link nuts. mine wasnt tight after i installed coilovers

 

my old sway bar end links were shot, replaced them with new ones after i installed the coilovers. still the same noise, even replaced the sway bar bushings with polyurethane ones.

 

di9d u thighten the sway abr links i forgot to tighten mine and my car sounded like ping ping ping when i came to a complete stop