PAC OS-2C BOSE OnStar Radio Replacement Interface for General Motors with Bose System Maintains operation of OnStar and factory Bose amplifiers for GM Class 2 Factory Stereos Onboard switching allows the OnStar system to play through front factory speakers and mutes the replacement stereo Provides an accessory turn-on wire Warning chimes retained Includes thePAC CM1 Chime Module Replaces factory radio in GM while retaining OnStar Plug &amp; play-no cutting or splicing into factory plug Communicates directly with OnStar module to prevent false triggering &amp; eliminating unwanted audio noise On-board amp will drive two 4-Watt speakers in stereo Use with existing factory speakers or external speakers