Everyone is right about trying to fix the Bose system that came with the car. I'm bitting the bullet with a new head unit and speakers. I have looked and everyone seems to be using different size speakers as replacements. It looks like the front uses 4x6 and the rear 6x9. I have a '89 Maxima, if that is of any help for size. I would like to use new speakers that could use existing holes. Has anyone tried to use the sub-woofer, under the dash, when they install a new system? Can the factory wiring be used or do I need to re-wire?