I'm not sure why, but on my 2013 DA42-VI, the G1000 equipment rack located under the rear baggage compartment floor was located within a metal HIRF box for RF shielding. In contrast, my 2008 Lycoming DA40 XLS with its G1000 equipment rack in the same place did not have a HIRF box, making it much easier to access the G1000 LRUs installed in the rack.
I'm guessing that regulators may have started requiring HIRF boxes for newer G1000 installations?