2003 cts engine noise
 

I looked at one tonight but passed due to unusual engine noise. It was at the top end in the engine and sounded like a chatter which increased with rpms, not the belts.
Are these known for top end engine noise?????? Don't know why it would be but is it normal?

If noise is audible with hood closed - not normal; with hood open - maybe. It's hard to advise about noises without being in the presence of the car. Some concerns require the presences of an experienced tech is necessary to advise you.