Damage my speakers?

If you are gonna run a rear channel, then you need to enclose the speakers. Whether or not the subs are firing right at them, in general, the sound preassure created by the subs in the trunk, will reak havuck on the rear speakers.

Chris

You could try these, I have never used them myself but, they might work.

http://www.crutchfield.com/S-ZixhFWEP6Id/cgi-bin/ProdView.asp?g=762&I=237XT65

Chris

Those little foam baffles from crutchfield do a great job of baffling the rear speakers from the air that the subs move in the trunk.  I've used them on mine since about two weeks after I got my subs.  For the price you can't beat em.  They still do not completely insulate those speakers from the interference caused by the subs.  To get an even greater degree of isolation from the trunk enclosure, build two small boxes out of mdf to seal those 6.5"s in.  Yet another option I've seen is using dynamat or something similar to fashion a baffle around those rear speakers.  I'm hoping that you've long since replaced your fronts with quality aftermarket parts, and you're not driving around with 10 year old factory speakers and missing hearing so much of your music that is drowned out by the subs in the back. 

just my $.02 ya know? 

I myself removed the 6X9 mounting plates from the rear of my Lumina Euro, built a set of adaptor plates out of 1/2" MDF then (using an old 6.5" that I had laying around), fiberglassed and actual enclosure for the rears. They sound much, much better.

Chris