2003 Pontiac Sunfire

if you have a cd player with your system, you are probaly best off leaving the deck alone.  removing it is not hard, pull on the panel till it pops off and unscrew it, but, it runs a lot of the things in your car, including the door chime.  There are modules to replace the door chime and whatnot, but its gonna cost you $$$$+++  changing the speakers shouldnt be too hard, I have a new bonneville, everything just sort of pops off, no screws.

Here is a link to a stereo removal: http://www.velocitymotorsport.com/install_notes/step_by_step.htm ( it's the second issue ) and you will only loose the door chime, nothing else with the '03 Sunfire's. The door speakers you will need to remove the panel and the rear's you will need to remove the rear deck to get at the screws on top.