Hi Guys, I am new to this forum but would love a bit of independent advise. I have got a RS4 2006 and recently, I have noticed dull knocking sound which increases in speed in sync with the engine when I rev it. It only seems to be there once the engine is hot and has been running for quite a long time. Is this something I need to worry about? Can anybody give me any advice as to what I should apart from the obvious. It has got 55k miles on it and has a full service history from Audi. I look forward to your responses. Thanks in advance, Czechneck.