Aftermarket unit in 09 vibe

[trasher]

I just ordered my 09 vibe yesterday, and it comes with the base cd player. (I didn't want to pay 600$ for the mp3/XM radio). For this price, we can get a better aftermarket unit with more features. But I'm looking for an harness, and I want to keep onstar features. I know it's more expensive, but I saw many site where it says "TBA". I emailed Metra about wich one I should get and they tell me I can choose between 2 models : GMOS-LAN-02 and GMOS-LAN-01.I don't know if my radio is pre-amplified or not. I don't think so but I'm not sure. Do someone have tried one of these harness on their 09 vibe ?thanks!(Oh sorry I just saw another post on this subject in this forum... sorry about that)