Hi guys, I have a 2006 monte carlo, its GM of course so it has ON STAR. I want to put an after market radio in there So I can adjust the output levels and setting for my other speakers. I currently have a sub/amp running off a LOC through my 6x9's. My question is what is the piece/part called that allows you to have an after market radio while having on star still functional. please post the name of this piece/part and cost if you happen to know of it. Also any head units that might be for sale, im looking for a jvc or pioneer only please. must be mp3 compatible with remote