My car when stock did 347 on a dynojet. That's close to average on a dynojet. Our Quattro likely looses 20+%. Were you at MAP?
Most well tuned RS6's do 400-425. (maxrs6 is a very special beast likely around 440awhp. IIRC Pats old beast did over 520 ft lbs. He decided to drop it back a bit after his trans was not liking it)
Your logs look ok. I think that N75 should be a bit higher. Is it stock?