This started out as a project to update the speakers in the doors and add a new amp. I really did not want to give up my cargo area with big sub box but after reading a post about a "JL Stealthbox" I decided to add a sub. The Stealthbox mounts on the side and takes up little space. Q-Logic makes a similar box.
During the install process I learned that the factory Bose cuts bass as you turn up the volume. So my new JL Audio amp and speakers were not going to work at their full potential. So I ordered a new Avic Z2 head unit and all the Avic "accessories".
My truck originally came with a Bose 6 disc system which I later upgraded to the Bose NAV. The 6 disk and NAV Bose systems are identical except for the head unit. The amp, speakers and wiring are the same.
The Bose systems use 6.5" speakers in the front doors, 5.25" speakers in the rears and small speakers in the dash for upper frequencies. The non Bose trucks appear to use 6.5" speakers the rear doors instead of 5.25".
For various parts of the project click the links below. This includes how to remove panels, route wire and almost everything required to install a complete or partial sound system in your trailblazer.
Special thanks to HakMazter for his insite on the project. Not to mention the clips and stuff he broke on his truck to figure this out so I would not have to !