[GBrutus]

The famous Mustang whistle is caused by the air flow over the gun ports at high angles of attack. It's difficult to see how this could be simulated in game but it would be nice.

its actually the airflow over the oil cooler, i have looked into this and the result was that the sound could not be added due to game limitations...

I'll need to dig up the source but I read somewhere about a P-51 owner who taped over the gun ports on his aircraft. The 'howl' or whistle was muted or significantly reduced enough to confirm that it was indeed the gun ports.