Absolutely. If you are replacing the factory amp with an aftermarket one because you can't interface with the factory stuff, yes. If you want to replace it so you can get more power out of the system then you should run new wires. Just be sure you know what you are hooking up to as far as the factory wiring (impedance, factory crossovers, etc). Myself, I like to interface with the factory amp equipment when possible as it is matched to the factory speakers and often has built in equalizers to make the cheap factory stuff sound pretty decent.