I had left the magnetometer wires long and not secured past middle cabin to facilitate hookup.
I finalized the routing, place the wire, measured for length, and then added the DB connectors.
From there, I could start securing the wire. I tried to route it away from other high current signals, but had to run it along side a shielded strobe cable for a while. There is no warning in the GRT manual about noise, so I assume that X,Y,Z are high level signals.
I ran the wire up the back of the rear baggage bulkhead. I used double sided tape anchors for zip-ties to assure that the cable can't rub against the fuselage.