Bose Speakers

your best bet would to just buy new speskers to replace the bose one's.

the reason for this is that bose uses their own amp to run their speakers in a factory system, all the extra wires you are seeing is for the wiring of each set of speakers to that amp, most bose speakers have multiple wire's and most have crossovers installed on each speaker.

You could connect the bose speakers to the other car, but the bose components that came in the nissan cars and most other factory installations are 1 ohm speakers. thus, if you did hook them up to something else, there would be little if any sound comming from them

There's supposed to be spots for 8 total speakers in 6 locations, and I know that for most chrysler vehicles they run the same wiring regardless of whether or not you get the infinity sound system.  The wiring is done in series so you don't have to worry about the extra speakers putting too much load on the head unit.

I'm pretty sure the extra speaker locations are gonna be just for tweeters, no bigger than 1.5 inches, but I could be wrong.  Technically in most chryslers you can put in 3.5s with a little extra work and creativity--I'd recommend that over just adding tweeters cuz you'll get more full sound with 3.5s.

Just look for a spot on each side of the vehicle that has what looks like a speaker grille, or spots where sound would be able to travel out.  They might be up in the rear side pillars, not sure yet.  Definitely let us know if you find anything out.