I fitted a set of these to my 55 today, along with some castor bolts. Goodness me! What a difference! I don't know quite what was wrong with the original kit, but it was hard and bumpy with, I think, quite poor damping control. The new kit feels more compliant and yet so much more composed. I drove home along one of my favourite twisties, looked down and I was going 30mph faster than I expected. A fantastic mod!