What servicing regime has the car been on? How long between all the services?
What type (LongLife or not), an spec (502.00, 503.00 or 504.00) oils have been used? What brand of oil has been used?
The FSI injectors are known to be noisy - and it is a normal trait of the engine.
Valve lifter problems are not common, and would only occur if servicing has been neglected, the wrong type of oil has been used, or even some lazy barsteward of an owner has refused to pull the dipstick and soley relied on the inaccurate oil level sensor!
A rare but significant noise problem is wear on the lobe which drives the high pressure FSI fuel pump, mounted at the battery end of the cylinder head. However, this seems to affect the Yanks, because they refuse to use the 504.00 LongLife3 oils which were specifically designed for FSI engines.
If you run the engine with the cover removed, you will make it run uneven, due to the lack of MAF (you may also store a fault code, which won't help).
Can you record a vid or mp3, and post it on YouTube or photobucket?