No, and I really don't like the way this was marketed. IMHO, just grab the STC Installation manual, the FAA Memorandum, the sample airplane flight manual supplement, an antenna installation drawing and just get the whole mess field approved.
The STC does not approv the physical installation of antennas anyway, nor does garmin give out those STCs.
One installer put the GPS antenna on the top of the tailcone on a Cessna177B, I thought it was lazy and stupid. I would want it in a good place, top of the cabin, so I can logically use that antenna for a WAAS/LPV navigator at some point, (top of the tailcone on that airplane really blinds the sides on the antenna)