Just a bit of a postscript to this. Since fitting new springs I have covered around 450 miles whilst carrying a fairly large case on the rack and two people. During that distance I have had a single noticeable spring to wood event. A short deep undulation in the road surface that I hit at speed and caused a bit of a bang. However compared to the old springs that is insignificant. With just two people and no luggage they perform superbly, very pleased. My only regret is that I didn’t fit the 4 seater springs as Dave did. Definitley will next time but for now the spring assits are going back on for that odd occasion.