Jim,

I have a PS Engineering 8000B audio panel and a Garmin 396 GPS. I've had
the combo over a year and have never had a problem.

The 396 is mounted on the yoke, I use the little stubby antenna only (the
Cardinal has a large sloping windscreen with plenty of sky for the unit to
see) and the XM antenna placed on the far left side of the glareshield. The
audio panel is in the top position in the radio stack.

I would be curious which GPS antenna your friend uses and which model PS
Eng. audio panel he has. If you have a chance to ask him, I'd be interested
to know.

Kobra