After a week of listening to the clunk of the Perrin rear sway bar and getting frustrated I needed to fix it myself. Here are some of the main things I tried. 1) Grease the bushings - sometimes the squeaking can sound like a clunk. 2) Keep endlink bolts tight. 3) Thinking it was the stock muffler hitting the new Perrin sway bar mounting bracket - I added Kartboy exhaust hangers to prevent exhaust movement. 4) The non-STi WRX's use "C" type endlinks. These with the new Perrin Sway Bar can interfere with each other. Grind down in some way either the endlink or sway bar where contact is made being careful not to compromise the structural integrity of these parts. No need to grind down too much, just enough for clearance. This is likely the cause of most of the noise. 5) Wrap the bolt holding the sway bar to the endlink with Teflon tape were the bolt comes into contact with the bar. The holes of the sway bar are slightly larger than the bolt and the tape should add some dampening to the movement of the bar on the bolt. I would say #4 was responsible for getting rid of 90% of the noise . That 10% might still be there but it is much more tolerable. If only I had pictures to make these more clear...
