haven't really got a definite answer on this. Is there a way I can keep the Onstar with this double din A/V nav receiver. Or what's the best thing to do? Is there a way I can put Sirius radio with it as well? and how? thanks

 

To keep Onstar, door chime, and the stereo to remain on until the door is open...you need this.
And it is compatible with Sirius.

 

Correct airborne227. That is for the base system. If you have the Monsoon system you'll need this:

GM Factory Integration Adapter General Motors Class II data bus interface — retains OnStar system, factory door chime, and Bose system with aftermarket radio at Crutchfield.com

 

This is perfect! thanks!