I posted this somewhere else, seems worth for posting here.
The package I put in my 2013 GT:
Pioneer AVIC-8200NEX
iDatalink Connec KIT-MUS1
iDatalink Maestro ADS-MRR Interface Module
Infinity Kappa 682.11cf
Rockford Fosgate P3SD2-8
Rockford Fosgate P2P3G-8
JL Audio Stealthbox
Alpine MRV-M250
SiriusXM SXV300V1 Tuner
iDatalink Maestro SAT1
Metra 40-CR10 Antenna Adapter
It cost some money, almost $1800 after price cuts, bargaining and rebates. It took about a month to find it all shopping deal, steals, Craigslist and eBay. I spent about 15 hrs programing, removing panels and such. Then uninstall the old gear and install the new stuff. The Kappa's in the doors and package shelf. The Rockford Fosgate sub's in the doors. The Stealthbox is in the cubby behind the right rear tire in the trunk. The Stealthbox was the most costly item at $600. The Alpine amp is in the trunk behind a carpet panel, mounted to a pillar on the left side. Short of having a big 7 inch touch display where all the knobs used to be and small red Fosgate emblems on the bottom of the door subs it all looks factory. I gave up a little trunk room, but too much. I stuck with the factory amps to eliminate some of the rewiring woes (RF interference, pulling carpet, seats...). I took my time soldering everything, using water proof shrink tube and putting down some dynamat like stuff while I was in there. I trimmed the door sub boxes a tiny bit (filled them with poly-fil), the package shelf next the seat belt pass through and a couple of plastic clips holding the shelf behind the seat. The GPS antenna went up under the package shelf in the rear. It receives 5 to 7 of the 11 available GPS satellites shown in the configuration screen. I Used the SAT1 adaptor to keep the OEM Satellite radio antenna. The Maestro unit kept all the Sync functions. While bringing many new OBDII features, gages, pressures, temps, throttle positions and such to the big screen. All the controls for environmental, Bluetooth, cell phone, navigation, Carplay, etc. is right on that same screen. I moved from the Dark Side of the Moon to Here comes the Sun and love the way it sounds. Technology ain't it grand!!!