[shorod]

Another thing to consider is it could possibly be a bad idler pulley and/or self tensioner, as well as a bad belt. When the A/C compressor is engaging, it is placing an increased load on the serpentine belt. If I recall correctly, you installed a Gatorback belt, which should be decent and not likely the problem, but I'm not a Goodyear fan (personal preference). However, if your self tensioner is not applying the proper amount of tension, it could be allowing the belt to slip slightly.

Does the whine change if you blip the throttle? How about it you turn the steering wheel to one of the locks and hold it there for less than 8 seconds, does that make the whine change pitch? What about turning the steering to lock with the A/C off, will it create a similar whine? If so, I'd suggest replacing the self tensioner and inspecting the idler.

-Rod