ya it is... i just popped out the rear speakers and those boxes today...
ya, i just need the sound fill... there IS a difference without them... i dont care if everyone says that their isnt much, to me there is.
some people take out the rear speakers to get the subwoofers waves to the cabin better, and when taking the speakers out, IT DOES help quite a bit. Though i will be putting my speakers back in... the sub is still heard and is very effective even with the speaker boxes intacted.
now with my new rear deck speakers, should i still use the nokia rear deck speaker BOX to hold the new rear deck speakers, and to help produce the sound waves(i think they might help), or just leave out the boxes and just screw the speakers (using the holes that kept the boxes up).