If you've got an S3 it's a k04. If you have an A3 it's a k03 unless it's been converted to a k04. Other than that you would have to look at the part number on the label on the turbo itself
If you gave a K04 turbo the diverter valve will be at the front of the engine. If it had a K03 the diverter valve will be on the turbo. In this photo the car has a K04 turbo and you can see the diverter valve between the front corner of the engine cover and the rubber seal of the black slam panel.
