the design of the rear suspension having a flex at that bushing is a good idea. if you got the $ get mugen replacements or the megan stuff if you want (been a while since i researched this shit). either way. it's more expensive to put in new rubber or hardened rubber replacements since that requires a press. if you wanna do it at home. buy the ES replacement bushings made out of polyurethane. you need to remove the rubber completely. leaving the metal ring. but you need to remove the rubber on the ring.

the piece in the middle of the bushing needs to be reused as well. but again remove all the rubber. easy to do with a wire wheel and electric gun. take note of how the cent piece sits in the bushing and try to reinstall in the same way (too left, or too right). makes alignment easier.

hih.