The only "fat" wire left in my plane was from the firewall passthrough to the starter stud. This is a #4 gauge wire with soldered lugs. It passes through the nylon passththrough for spark plug wires and has to be routed to remain rigid in relation to the engine, but flexible as it jumps over to the firewall. I accomplished this by leaving a slight loop between the passthrough and the Adel clamps on the engine mount. During this session, I also routed and protected the brake lines as they pass under the pilot and passenger seats.