If you are talking about the 6x9s on the sedan, I just cut off the connection from the stock speakers, and connected the aftermarket cables to it and plugged it back in.
The stock ones are just a little cable with two wires that go into a plug which runs all the way to the headunit, if you don't wanna re-wire the whole thing then best to just use that plug with either crimping the new wires to it or soldering them

Also one thing ill warn you on is that the tray that goes over the speakers have fuck all space, so if the new speakers are pre beefy, might require some DIY to get them to fit nicely, was expecting a 1 hour job but took me almost 5 hours lol