Have 03 Ultra and back speakers are rattling and need replaced. Upon research I find out the Ultra has the 9 speaker setup and the rear deck speakers are hooked up to the amplifier and only play bass. Some comments have been to unhook amp and replace back speakers and leave amp off to get a better sound. Anyone have any info on this? I believe rear deck speakers are 6x9? Any thoughts on what brand of speaker to buy and can I uninstall and install speakers from trunk after dropping amp? Anybody maybe have pics of their uninstall procedure?

I looked up the wiring diagrams, and I see a 6 speaker system(no amp) and a 9 speaker system(Uses an amplifier).........

So I would assume you have the premium system, and you probably have an Onstar.....

By the way all your speakers are hooked up to the amp....

By the way all your speakers are hooked up to the amp....

Not sure if you are going to get better sound by disconnecting power to the amp, and not sure the signal goes through the amp to the speakers if you remove power to it.....if you disconnect the harness to the amp, you have to rewire 9 speakers....