Haha, I was also not keen to cut... Thing is that it does not affect the rigidity of the car and it's easy to hide - from inside the car there is that plastic cover behind the armrest and from the boot, just carpet over it. I'm sure I could get a new firewall at a scrapyeard for cheap if I needed to.
To access the rear speakers just pry open the speaker covers with a flat screwdriver - they just pop off.
I would advise you to rather upgrade the front speakers, the rear speakers are not as important - your ears face forwards
Rear speakers are normally used to create ambience or if you have passengers in the back, then for them. One would ideally want the music to be comming from the front - as if you were at a live concert. Bass is a non-directional frequency, that's why it does not affect the sound stage having your sub behind you. Unless you got the bass turned up too loud - then it becomes directional.
...woah, how did I end up giving you a sound quality lecture.... sorry buddy, force of habbit I guess.
