If you have Bose & On-Star and you do a full system replacement(4 channel) you will lose the door chime. The door chime is produced in the amp inside the center console, and nobody that I know of has a Bose/On-Star interface with the external chime. I went through Crutchfield and they told me to wire and extra speaker to the drivers door output in the center console. I believe the adapter I bought was a GMOS-04.