Alright people... this is my opinion on the clunk. Its the poly bushings. The polyurethane transfers the vibration of the rear susp into the frame. just like poly motor mounts transfer vib. into car. I have investigated this and it seems that many makes have "clunking" issues when using large diameter bars and poly bushings. BMW, Honda/Acura, etc.. owners have had the exact same problems as msp and protege aftermarket sway bar users. I believe that, especially during bad weather,temp extremes, poor pavement, the poly will always have a clunk/ sqeak. Unless u grease it weekly and replace the bushings regularly(cause they do wear) it will never go away. The only choice is to replace it with either the prototype mounts or rubber bushings. the rubber will withstand alot more but may have a slight perf. impact. I am gonna try the rubber... if that doesnt work i will use the new mounts with Energy susp bushings. These might also be a good idea as opposed to mazda's constant bushing revisions.