Thanks Rick.

Martins in Belgium at the mo so wont see the post, but the adjustable rear trailing arm allows both positive and negative adjustment of castor. It also helps keep the back end a little tighter on hard cornering by doing away with some of the rubber bushes.

Parallel arms will do as Rick says and basically stop the rear wheels from trying to steer the car on cornering, and allow infinate adjustment of camber and toe settings. At the end of the day it can give you much better stability at speed or make it corner like its on rails.

HTH