When referencing our new harness I always tell people, if you are capable of removing your old harness without cutting and hacking it to pieces, then you are more than capable of installing our new harness. You can even do half of the install with your dash out of the vehicle and in the house in the heat/air conditioning.
If I had to put a guess on how long it would take for someone to intsall our harness I would say about 3 full days.
day 1- familiarizing yourself with the harness and manual, removing the old harness and removing the dash from the vehicle
day 2- installing the fuseblock/glovebox and harness into the dash, re-installing the dash , and routing & installing the tail section
day 3- routing and installing the headlight section of wires, routing and installing the engine section of wires.
if you spend some time before your actual install going over the new harness, it makes installation a lot easier. The harness almost becomes a "system" and not so much a big glob of wires in an tangled mess.