Looking for a little guidance. My Cessna 182Q was just upgraded with a GTN650 and BK Aerocruze (Trutrak) autopilot. Plane has an original 6 pack with the exception of a GI-106A CDI. Before the install the avionics shop told me that this setup would be capable of performing GPSS approaches which is the main reason for this install. After a few attempts to get this to work without success, they're now telling me that it will require G5's for GPSS to function. Supposedly, this is because the GTN650 needs a barometric corrected altitude to engage. The shop is not a Garmin dealer. I was originally told that since the GTN650 is WAAS, it can do GPSS approaches. I'm receiving conflicting information now so was reaching out to the world in desperation for guidance. The plane flies perfect in track and GPS mode, but alas no GPSS. Bottom line question - can the GTN650 fly coupled GPSS approaches/holds/etc with the BK Aerocruze autopilot without G5's?