I covered over the map box hole with a plate and built rails between the panel and sub panel for mounting boxes.
The pilot side has a GTR 20 radio, the co-pilot side has the GTX 23ES transponder with the GDL 39R ADS-B piggybacked. (The case for the transponder has to be removed from its mount before the transponder can be slid out of the case.)
I used the sub panel to mount the GAD 29, GEA 24 and a TCW IPS.
RV-14A Builder - kit #136
N314KC - First flight Mar 8, 2017, Phase I compl Apr 3, 2017, >180 hrs
Sport Pilot (weight-shift control) - Airborne XT912
Dues paid 11/2017