So I pulled the undertray and proceeded to try to one by one disconnect harnesses in order to make the sound go away and diagnose it. Voltage regulator, transmission harness, fan harnesses, etc, nothing.

Then I went to the fuse box in the glove box and one by one disconnected fuses. Fuse 41, rain sensor made it go away. The headliner is out as I've been sealing the sunroof. I'm still at a loss as to where the sound is coming from but it has to do with that fuse. Very odd