16v's aint the quietist of idling engines both mine were very rattly and sounded a bit like a sewing machine idling but ive found that changing the timing chain and hydraulic lifters will remove 95% of the noise!!!!
over easter there i got a fair bit of work done to mine and i must admit the results are stunning. engine is quiet as a mouse now idling and sounds sweet as - its like a new car!!
best £250 i ever spent of which £150 was the parts
work done was:-
timing belt
tensioner
timing chain
lifters