4.8is trans "hoot"

[Siege87]

Hello all- I recent have started to hear a "hoot" noise coming from my trans when I start to accelerate under a good amount to throttle, and when the trans shifts (also when giving it a good amount of throttle). The issue has previously been talked about here-
http://www.xoutpost.com/bmw-sav-foru...-software.html
and in 2 or 3 other threads, but nothing recently. The dealer says it isn't throwing any codes, and that it might be noise from something rubbing when the trans/engine is torqued under these conditions. They don't think it could be a trans fluid issue and they already reset the software (no improvement).
Any ideas, or has anyone else encountered this problem recently?
Thanks much!