Both amps were installed prior to the BT module being installed and they are tied to a distribution block which is grounded to the metal under the rear deck.

Prior to installing the BT module there was no noise in the system - it was only after I put the BT module in.

As the BT ties into the audio system but grounds to a sep location I am going to run an additional ground wire from the distribution block to the ground pin on the 12 pin oem stereo harness (the one that carried the power/ground/woofer connections) to try and tie the grounds together. I just haven't gotten to it yet.