Under the seats there are electrical connectors for seatbelts, heaters, and airbags.
The airbag connect is different, so I had to cut the connector off the original seats and then remove/splice it to the GTI seats.
The seatbelt connectors were the same.
The heated seat connectors were the same, but you dont have wiring so it doesnt matter.
If one day you do want to hook up the heated seats, there are multiple threads at vwvortex or TDI that provide all the details.
Used the VAGcom to clear the codes and accept the new seats.
The seats make any corner more fun, and in full recline mode are comfy enough for a nap (verified).