Boxes for components ?

Most components are not made for small sealed enclosures.  I personally wouldn't spend money on components for rear fill.  If you want some fill back there some cheap coax speakers should be fine.

kfr01's got a point.  Back end's not the place for comonents.  You want to stage you're music so bring all the highs to the front.  Go with a 5.25 for the back or less.  You could put them in a larger sealed area especially of they're open to the trunk and you've got a "sealed trunk with a sub.  The sub's pressure can interfere with the speakers playing ability. 

Well I think by adding speakers (coax or components) to the rear deck facing veritically I will benefit pretty good since all off my other speakers (components) are at close to floor level. The sound reflection off of the rear glass should give me the on-ear plain that I am hoping to get, plus if I have extra speakers that are pretty decent I might as well put them somewhere right. 

Nice, yeah I would kinda like to get my car heading in the SQ comp. car area.

Jeff, how many speakers do you run in the SQ car ?

http://www.crutchfield.com/S-Fn08JkHasQ1/cgi-bin/ProdView.asp?i=237XT62&id=morephotos&a=&s=0&cc=01&g=762#morephotos

Foam baffles like this are a cheap way to help kill some of the subwoofer interferrence.