help with rear speakers??

[spot_on_jon]

iam looking at doing my audio, just rated me front door speakers, and now have a sub, now iam looking into getting sound from the back end of the car, ive been told to stay away from 6x9s (sumthin to do with the quality of sound) so iam looking at doing something like this......



any1 have any idea what sizes can be fitted in this area and how much work it will be??


any help would be sweet