I just had my turbo replaced on my 01 S3. I managed to find a K04-022 the shop fitted it for me and retuned the old unit to me... Funny thing is it looked slightly different? The model number on it said K04-023... and when I do a search on the net I found that my car came out with the K04-022?
So these are both BW KKK turbo's.... however! With my new one fitted my car feels stronger and when I liftoff below 3000rpm i hear a flutter.
Anything to be worried about?