A friend of mine, more mechanically-inclined than me, helped to install my GT3 seats this weekend.
They look and feel great!
Before the install...
Factory Sport Seats:

GT3 Seats as delivered from Southcoast Porsche:
One of the two seats did have very minor damage to the belt loop plastic and minor blemish to leather where the other seat adjustment handle made contact during transit.
During the install...
Removed the factory driver seat:
Once the seat was removed, we identified the various wiring harnesses and connectors. The only one that can be used with the GT3 seats is the seat belt connector.
Here is it re-assembled in the wiring connection box and installed on the factory mounting point under the GT3 seats (gotta luv OEM equipment)...
Installing the seat belt to the new GT3 seat.
Finished!
This 1 hour project turned out to be 3 hours, but we took our time and much care removing and installing the seats. There were many points this could have been ugly (damaging parts on car) had much time/care not been taken.
Thanks so much for your help Dave!
Gary