i'm sure someone has accomplished that before

 

Not without cutting...but i did it too my other 95 4dr, not hard

 

 

Although not that hard to do, it's not worth doing as rear speakers should be for rear fill only, 6.5" speakers can easily supply rear fill, also not worth weakening the rear deck by cutting it up. 94

 

IF those 6 x 9 cannot fix at the rear then just make a box for it. If you believe that theives would take it then don't bother putting it at the back. Would bother cutting the rear deck because it make look bad.

 

Indeed right here....idk if ill even put anything in the rear my new project Civic honestly.

 

A mono rear fill, [no highs] can help imaging, move sound-stage up and eliminate left/right bias on the front speakers. 94

 

Yeh...thats all im concerned with...nothing crazy SQ but i do want a good image on the front dash.

You mean like a center stage in the rear or none?

 

Doh!!, I missed the OPs question, 6x9s in the front doors, [not the rear deck].
Absolutely not worth it, and never cut your doors if you do not have to.

Skip01
Technically you only need 2 speakers, there are only two channels in stereo, a left and a right.

Because a car is a poor "sound room" it can be very hard to get good staging and imaging, because the front speakers are almost always installed in the doors, low and to the left and right of you instead of in front of you an undesirable thing happens, "left/right bias", if you close your eyes while listening to the music you hear the music coming from the speakers, meaning if you "look", [eyes closed] towards where the sound is coming from and then opened your eyes you would be looking at a speaker, the left or right one instead of straight ahead, like "5th row center" at a concert hall.
Left/right bias can pretty much eliminated by adding rear fill, mid-range and lower only, no tweeters, [highs] high frequencies are very directional, [easy to hear where they are comming from] so highs behind you will tend to move the sound stage back, not a good thing, stereo, [left and right information] behind you will also move the sound stage back and make proper imaging very hard if not imposible the solution is to have a mono or mixed mono signal behind you, take any pair of rear speakers, [even stock ones], disable/remove tweeters, wire the speakers in series to increase impedance and wire them to a mono or bridged amp, cross them over as low-pass 5000Hz or lower, try it you will like it. 94