the AXR clunk fix brackets will make a noticeable difference in handling. apart from fixing the clunk issue, it relocates the bushing to make the sway bar more effective.
point of interest: mazda contracted racing beat to develop the suspension for the MP3 (and by extension, the MSP), and their design for the rear sway bar included similar brackets. however, due to costing, mazda chose not to incorporate the brackets in the production configuration.