Soundgate makes an interface called the digistar b. It lets all the onstar functions still work with an aftermarket head they go for 149.95 + shipping. I bought one to install an in dash dvd but have been sinking money into building my new house. If you are interested in it let me know and I wil give you a good price. It is still unopened and it is brand new. I got it from logjam.On Star interface