If you wanted to use the factory amplifier it becomes complicated because you would have to get a pigtail and run a part of the harness back there. If you were to wire it up with an aftermarket amp to the factory speaker it could simplify things for you. I just used an older 2 speaker box with JBL speakers and an aftermarket amp before to upgrade my 2012 (Shaker 500) I used to have. It comes down to your preference and how much effort you want to make it factory style. I like the factory look with the aftermarket performance. Hope that helps.
T.L.
I verified i still have the pigtails i cut off. Plugs have about 3" of wire on them so they would have to be extended. They are free with the lights if you need them.