3 hrs. working out the sub-panel arrangement and starting to build it out.

The brackets that come with the kit are for an older transponder, and unfortunately they don't work with the GTX 45R ADS-B/Transponder I have.

I was going to put the TCU on the sub-panel, but decided it would be best put on the cabin-side of the firewall near the large pass-through hole (not cut in the soundproofing yet).

After much contemplation and swapping around, I decided on this final arrangement.  The center section is completely clear leaving lots of room for the GTN 650 and anything else that will pass through the center.

Another view.

Time to start drilling!  Some of these could be held up with M3 screws, but I have better luck with the M4 rivnuts, so I'll standardize on that size.

Rivnuts in for the GEA 24!

And it's in!  I'll pass the wiring going to the engine from that box right through that hole.

Next up is the backup battery and that's in too!  I'm hoping to finish this all up tomorrow.