so as I was driving yesterday, I was going a little hard, got the tires spinning into a turn and immediately after a disturbingly loud noise came from the pass side speaker. I pulled over to inspect, turned the car off and even removed the HU and the noise was still there! extremely loud too! eventually after a few minutes I turned the car back on and it got real loud as the engine turned then went away... and now they sound fine again. I'm guessing it's some sort of wireless interference? not sure.... any suggestions?

 

In order for the sound to be loud, it needs some power behind it, which
it's not getting from the headunit if it's removed. Do you have an amp?

 

yeah a 4 way amp... perhaps there's a bad connection somewhere? the ground maybe got loose?