Slk 200 top end noise has me baffled?
 

Well I m at a loss regarding the diagnosis of the top end noise on my 2007 slk 200 with only 35k on the clock.
Tapping noise when cold for around 2 minutes reduced to a few seconds when hot. Once the tap has gone the engine is a smooth as silk suggesting some sort of oil pressure issue.

Thing is at great expensive I have replaced with new mb parts the following.

Both camshaft adjusters
16 lifters
16 roller rockers
Timing chain
Timing chain tensioner

I really am at a loss as to what the problem is so any help is welcome.

Thanks