I know this is older but figured it warranted a reply.
I drilled a hole on the passenger side up high underneath the carpet near the ac evap box. I originally had the wires and rcas ran along the side door trim to the rear and it had an audible ground loop whine that followed rpm. I re-ran the power wire down the center of the car under the center console and now its whisper quiet. I can post a pic if anyone needs one for reference.
'03 Marauder 300A / Forged 11:1 Eaton @ 17 lbs - 87 Octane
decipha @ EFIDynoTuning