OK, I have a 496, and an air gizmo mount, which I'd like to put on my
panel. I'm curious to the signoffs needed:

The Air gizmo I think should be allowed to be installed by the
owner/pilot as an interior decoration as long as it doesn't involve
drilling or cutting the panel. Correct? If I have to cut the panel or
drill holes, do I need an A&P signature? The W&B change is negligible I
believe.

In order to wire the power into the aircraft power (not through a cigar
lighter plug), I think I need an A&P signature, and all work has to
conform to 43.13, nothing more correct?

How about running extension wires for the XM USB and remote antenna to
the top of the glareshield with the wires behind the panel? I imagine
that needs an A&P sign-off if the wires are tie-wrapped into place?

OK, and the final question: It looks like in order to fit it in, I'll
need to pull the ancient Foster Loran and it's tray out. That's surely
going to need somebody's sign-off. Does that have to be pulled by an
avionics shop (it does have a connection to the autopilot switch), or
can that be done under an A&P's supervision and signature as well? I
figure I'll replace the Loran antenna with a comm antenna and leave the
end available on the panel for my handheld.