As coming to getting my new car. I have always noticed and thought the 09 engine was much better although the same power etc. After checking the chasis number I currently have a CDL which is the newer engine " Chain driven I'm led to believe ".
It seems to oull much stronger and seems a tad more responsive.
See what you have as In my orange S3 it was a BHZ.
Scroll down a little
Just a note to reference.