Squealing sound over back right Mach 460 speaker

[Five O]

So whenever I take a somewhat sharp left, there's this weird squealing noise that comes from only the back passenger-side speaker. I have the Mach 460 system and as far as I can tell everything is stock (stock AM/FM Cassette HU). Any idea what this could be?

 

[ttocs]

sounds like there is a bad connection somewhere. Power the sytem up and go back and try to bump/tap the speaker/amps and try to pull/tug on the wires going to it too see if you can find a spot that when you mess with it, you hear the noise. Once you find the problem then we can figure out what to do next with it.