I would atleast disconnect the sub, you dont have to take it out.

Its most likely that you will not be able to hear the bose sub over an aftermarket sub.

 

If I actually get to do this this summer, im replacing the front speakers with cdt components, disconnecting the rear door spks and putting in a sub or 2 and making a fiberglass enclosure for that.

I can't see anyway possible that adding a sub and keeping the other bose speakers would sound good at all..bleh

 

cant u just replace ur rear sub? any pix?