The factory setup will have small amplifiers you may end up dealing with. The problem can be the fact that theyre made for one kind of input from the OEM headunit and youre changing it to something else. You may end up with broken amps or speakers. If you dont care, go ahead and just swap it out using a haness that plugs into the back of your aftermarket headunit and connect that into the factory wiring. If you plan to upgrade the rest later, go ahead, because youll be swapping things out anyway. If youre on the cautious side, replace the speakers, headunit and run new wires and completely bypass the factory audio system and its cables. When I did my audio, I only used the factory ground and power cables in my factory harness to power the headunit. I ran all new cables for everything else. Now im not saying youre going to get catastrophic results after swapping out headunits, but just so you know, that its possible that OEM things can break, because youre using a different headunit, thats all. If you check in audio stores, they should be able to tell you what harness you will need to plug into the back of your headunit to connect to the harness thats in the car. You can also look in the car manual to find the wiring diagram and find the cables there as well. If you dont have the manual, see if you can find one or buy one. Hope this helps you out at least somewhat. Good luck.
