definately very very true....crappy installation can lead to crappy sound and more problems even with the best parts....
if your looking to save some room by not getting a sub there are several people here who have build subs into the rear door....they just take the spare tire out and build a wood enclosure to fit there....
the VX actually has a lot of room to put amps under the front seat so dont be afraid to get in there...you will however have to bend that metal plate on the back of the seat or your seat wont go forward and back anymore...(sorry i know thats not what your looking for, i just get excited and want to add more and more when i think or talk about audio stuff)