I've seen that you have to buy some type or harness so you don't throw engine. Is this true? It costs about $80. Anyone installed an aftermarket cd player in a cobalt? I'
 
Yeah, you're really gonna haveta put in the extras to do an aftermarket radio addition.  As part of the deal to get my G5, they put in the in-dash 6 CD radio.  Even with factory parts, there was a computer re-flash involved for the new radio.  Good sounding OE radio and speakers, if you ask me.
 
UMMMM yea i just put in an aftermarket radio and everything works fine with out the damn T harness. Its a scam to get money out of you i promise.