My 2001 3.8 9C3 Impala used to produce the whine sound during a hard acceleration. The problem was fixed after the two original suspension bushings of the dog bone engine mounts (at the frame ends) were replaced with the Polyurethane ones bought from this link:
http://www.3800performance.com/Merch...roduct_Count=0
It was discussed in this site that the original bushings allowed too much room for the engine to move during a load.
However, with the polyurethane bushings, the car body vibes a little more than usual, during idles.
Hope that help.
James