Mach 1 making a whistling sound when it is cold. Is this normal?

[Reimann]

The whistle is quite loud and can stick around for a while. It whistles the most during acceleration but will do it while idling too. It can do it when it is as low as 50 degrees outside and gets louder the colder it is. Also, while idling pushing on the break changes how it sounds. Is this normal or a sign or a problem?

 

[SaleenGT2001]

belt squealing??

 

[Jbauer]

a lot of mustangs whistle during the cold in the mornings.
I think it's the intake.
Get use to it..you'll probably never find a solution. i kinda like it

 

[Reimann]

It doesn't bother me too much as long as nothing is wrong and there is no damage. The car doesn't seem to perform any differently, just noisier.