OP,
I have had the same whistling sound upon accelerations for the last few months. Interestingly my idling has been fluctuating a lot in the same time frame and I was reading about the idle control valve going bad as a reason for the fluctuating idling. So not sure if its all related.
The sound is annoying and bothered me initially but I just ignored it telling myself maybe its one of the many abnormal sounds associated with our cars. If something is indeed going bad I hope the car will let us know in some other way
.
Anyways please keep us posted if you find anything more. Thanks!