Car: 05 Coupe, Stock calipers with Project Mu HC+ pad (only get these if your only concern is stopping...they are noisy and dusty)

I'm just trying to get a few opinions about what it could be because I don't have a shop to work in and it is in the 30s and windy, so I'd like to have a plan of attack.

So the issue I think I have is a brake dragging just enough to make it sound like a record player needle is dragging along my rotor. (I can't hear it if I listen to the stereo louder than 10) I'm thinking that some salt may have gotten kicked up onto the caliper and is causing it to not slide properly, with the combination of the semi metallic pads is making the noise??

Any other ideas of what it could be/solutions to those problems?

 

Maybe parking brake.

 

Were the rotors and pads replaced at the same time?

Was the rear axle perhaps removed at anytime?