GT Audio Expansion Question

Hi, I am interested in getting a G6 GT coupe and my question concerns the Monsoon stereo system that comes with it. Now, I like to expand the audio equipment in any car I have, basically replacing the stock stuff with aftermarket goodies. I've done this with the car I currently drive (02 Grand Am SE), but I hear that this can sometimes cause difficulty in GM Cars with the Monsoon stereo system in it. Is this true? What can I expect if I want to replace the system with aftermarket equipment (e.g. new head unit, speakers, subs)? Thanks.

p.s. I already know that replacing the stock head unit may mess up the "chimes" in the car (e.g. when the car just starts, the door is open, you're driving w/o a seatbelt, etc.) because this happened in my Grand Am.

Hi, I am interested in getting a G6 GT coupe and my question concerns the Monsoon stereo system that comes with it. Now, I like to expand the audio equipment in any car I have, basically replacing the stock stuff with aftermarket goodies. I've done this with the car I currently drive (02 Grand Am SE), but I hear that this can sometimes cause difficulty in GM Cars with the Monsoon stereo system in it. Is this true? What can I expect if I want to replace the system with aftermarket equipment (e.g. new head unit, speakers, subs)? Thanks.

p.s. I already know that replacing the stock head unit may mess up the "chimes" in the car (e.g. when the car just starts, the door is open, you're driving w/o a seatbelt, etc.) because this happened in my Grand Am.
I have the monsoon in my GrandAM and the factory AMP is mounted on the side of the trunk.. I had a 10" woofer installed in the trunk and basically some guy just ran pwr from the battery and used one of the fuses in the drivers side panel for pwr.. Then he just piggyback a couple of wires from the amp itself.. I still have the 2 6X9's playing put just disconnected the two wires that run the bass so I can have all the sound coming from from my woofer. So basically nothing was done to the factory radio, everything was just wired off the factory amp..