In one of my very old Aeromodeller or Model Aircraft magazines Peter Chinn was complaining about the Super Tigre numbering system.

The "G" does indeed stand for Garofali and the number, as far as I can recall, is the "series" number which is basically determined the the crank case casting. I STILL find the various G numbers very confusing, but then have only had a couple of Super Tigres; a nice racing 29 RV and one of the fast 15's of the 70's

Charles