[CivicSiRacer]

Bushing help isolate vibrations and also help in suspension parts in making them move easier. All are made of rubber. And of course rubber can wear out, and if you get an upgraded suspension it will not work as well with worn out bushings.

You have motor mount bushings which isolate vibration from the motor. These car rip and tear as the car gets older.

And you have suspension bushings which are compressed, turned, squashed and exposed to road dirt and salt. These will wear out too.

They look like basically rubber tubes that get inserted in joints. Most street cars come with soft bushings which makes them nice for everyday driving.

Aftermarket bushings like Energy Suspension or Prothane have a harder durometer (hardness scale) so your suspension works better and handles better at the cost of more vibration and stiffer ride.

I installed the whole ES bushing kit since the rules for autocrossing in my class allow it. This is one of the best upgrades I've done. Although I do have to keep on top of greasing the bushings once in awhile.