I just bought the Double Din Kit and the W200 Alpine. I don't really want to spend the money for speakers right now. Can I use the factory or they will only work with the Bose Head Unit?

 

It'll work but..... it won't be pretty unless you know what you're doing with the wiring of everything.

 

You may need to get one of the various adapters to allow you to run your new head unit through the Bose amplifier. Otherwise, you'll feed way too much voltage.

The best thing you can do is to avoid using the Bosa amp at all. Bypass it even if you have to keep the Bose speakers. Try to replace the bose speakers before too long though.