I did my tappets a couple of months ago and while this quietened the top end considerably there was still some noise. I did not replace the timing chain tensioner at this stage because I did not want to change two things at once and also there was a reply to an earlier post of mine about top end noise,which I can't find,telling me that a worn tensioner can cause noise.Two months on I have just changed the tensioner, I used a Febi Bilstein which cost me £36, and the top end is certainly quieter so thanks for the tip. An interesting point is that when I turned the engine slightly to release the spring instead of the usual click there was more of a 'buzz' which was the clip running up the serrations. This could indicate that the tensioner was worn despite the fact that the previous owner said that it had been replaced.