The speakers and wires can definitely stay. The main thing you have to be concerned about is whether there is a separate amp in the car, because you might need to wire around it. As you don't have the premium sound system from the factory in this car, there probably isn't an amp, besides what was in the original head unit. How many speakers are there around the cabin? If it's just six or eight, then there probably isn't a separate amp. If there is a subwoofer (check the trunk), then there probably is an amp.