Review on Metra GMOS OnStar Interface Systems by Zachary Caldwell

Compared to PAC, that's 5 stars. But it's still garbage. The PAC call sounds awful. The "give me my money back you idiots" kind of thing is awful. The doorbell goes through the speakers, not the 25 cent speaker that comes with the PAC. PAC straps are very loose and will fall out and make a hissing noise. These are better. If you're adding an aftermarket amp, don't take this one. Get the cheaper one that doesn't need Bose. GMs have a standard wiring harness behind the airbag key or behind a drawer next to the air conditioning/heater controls. It's hidden behind a frame with stereo and air conditioning controls. Use this plug to bypass the original amp. Much luck.