Any light clicking and clacking from the valvetrain? When I bought my car, I asked the guy about the noise, he said it was normal. Even fired up another A6 4.2, and an A8, and they sounded the same. I've always wondered though...

RPM dependend clicking. Sounds like an injector click or valve tapping. Can only hear this with the hood open.

I wish the V8 was whisper smooth but I guess it's not.

Oil says right up there so far, by the way (43,000 miles).

can't say I cared to figure out for sure whether it was injectors or valvetrain noise - probably mostly valves.