I've just changed my Koni FSD's to Koni adjustable Yellows. First set of FSD's were knocking mostly when travelling slowly over bumpy/rutted surfaces. They were replaced under warranty and were then quiet for a while, but they've been knocking for the last couple of years. It was quite a common problem with the series 3 Comps. Anyway the new ones are great with no loss of comfort or road holding - just no damn knocking.