Where is the grounding point for the stock fosgate head unit? I am trying to track down a very annoying alternator whine and I need to make sure my amp ground is the same potential as the head unit.

edit. or is it through the harness?

 

more details on your setup would help.

 

nevermind. I was looking for a common ground point/screw to try and equalize ground potentials but I found the problem elsewhere. Turns out that 12v to 5v usb adapters to power smart phones are noisy as all hell. All of them. I hardwired a car charger to run my Droid for Pandora in the car, and the adapter makes a retarded amount of interferance. Gonna have to solder in a filter cap and try again.