+2 with Jason on the air bag. You shouldn't be removing any electronic component in that vehicle with the battery still attached whether through the emergency cut off or complete removal.
Here's a short write up on the heater core:
Maserati Heater Core | craig-waterman.com
Additionally, since I will be doing this in my GS this winter season, I also am looking into having a brass unit built, brassworks, no offense, is a bit expensive and they don't cost that much to build. Matter of factly many times the cores themselves are the same size as other vehicles, and the inlet/outlet tubes are just soldered on. Someone correctly identified it like a radiator, which is nothing more than a heat exchanger. Brass/copper cores also had their down falls and that should also be understood/researched.
As to them figuring out bad design for cores that still goes on to this date. I've seen brand new Camaros ripped apart for this same issue. Actually, many different makes and models you'd think of already gotten this correct, when so much work is involved. To be quite honest, though it's not as messy as replacing the clutch, because you are laying inside the vehicle, I would rather change the clutch in this vehicle than the heater core for various reasons. One is just all the cheap plastic laying in wait for you as you do so.
If you are doing this in a Coupe take the seats out, and cover them. It will give you more room, and space. You don't want to be rubbing up and down all over your leather seats during this process, especially with the tar like sticky pieces you are going to encounter.
Second, you don't have to remove the steering wheel, loosen the column and work around it. In either case, I did not do a write up on this because it definitely would have been a really long one for each and every bolt, nut or screw.
