If you have an interest in the 2004 A4DE you may care to follow This Thread: and This Thread:
You will read about a pretty gutsy effort by the Kiwi Team captain who in true Enduro spirit replaced the cylinder head in less than ideal conditions! Without that effort the team would not have been on the rostrum.
There are 9 pages of thread, (plus links), so you need to be a speed reader or have a bit of spare time