I did the installation and it worked fine. Attaching the 13 pin to the ground at the top of the radio has eliminated the ground loop hum.
Only one problem. While completing the installation, I managed to pull out the antenna wire from the radio. It appears to be a devil to reattach it. I contacted the Subaru service people about it and they said it required a special tool which they did not have.
Anyone out there no how to reattach the antenna wire to the radio?