Well I work at Best Buy and install both all day long. We get a lot more sirius than we do XM they all sound alright if you get the wired FM mod but you have to have one. I like sirius better because of the programing and I like their unit's better. If you want the best sound get one that hooks directly to your deck. Hope that helps
If I have a sirius reciever already, how much would it cost for you guys to hook it up to my in car system? Its one of those built in console type things, not a removable din or double din unit.