What I noticed: Due to the sports suspensions, the original plastic bushes were no longer doing their job efficiently and generally decreasing the car's steering response.

After fitting the Polyurethane aftermarket bushes these problems have disappeared. The steering has become much sharper i.e. more responsive. I haven't noticed much increase in road vibration, if anything the car seems to handle better overall, this is including over speed bumps and pot holes. This mod is a must for anyone running aftermarket suspensions.