The problem you are going to run into is that the factory speaker wires go into a connector that plugs into the stock stereo. If you go with an after market head unit, you will have to identify the speaker wires that go to this connector and cut them off to connect them to the new head unit. There may be an adapter available, but that will be a little costly. If you are running 45 watts or so to each speaker, the small gauge factory wires are not really big enough to handle the power. That is why stereo shops routinely install new wiring to the speakers. It is not hard to run new wiring, there are several write ups over in the audio section of this forum that explain how to remove door panels, seats, and carpet to allow you to hide the wiring. If you cut corners on your installation, it will cause you many problems down the road. Do it right the first time. Good luck….Dwayne