Today's modern vehicle audio systems are becoming increasingly more sophisticated and complex. PAC® Audio engineered this AmpPRO4 Interface to improve your vehicle's audio performance while keeping the original radio’s fit and finish. The AP4-GM81 simplifies the installation of upgraded amplifiers in select Chevrolet® vehicles with Bose® A2B factory amplified systems. This amplifier integration interface also allows you to retain important factory features and provides navigation outputs. It also comes with a sublevel controller. Please note the factory amp must be removed from the vehicle while installing this interface. .