Does anyone happen to know which harness I get for my 2008 Cobalt Sport that has XM & Onstar?

I have found that I need the GMOS-LAN-04 harness over the 03 but I am going to be installing all of my gear which is deck/speakers/subs/amps (infinity 7541a & 1211a) and replacing the Factory Pioneer system so its confusing me.

Pictures of all my gear are in my car domain in my signature on page 2.

 

Metra says it needs the GMOS-LAN-04. This harness will retain OnStar but the XM Radio is part of the factory GM Radio I believe.

 

Ya I know that and have Sirius so that is not a big deal, I just wanted to know If I still need that harness even if im bypassing the factory amp with my own.

 

Yes because that harness does more than bypass factory stereo.

 

Perfect thanks.