MethodX

Hey guys, I know I'm reviving an old thread but I haven't found any new information... I just got my 2008 IS 350. I currently have a XMDirect Universal Tuner and an adapter for connecting to a Sony head unit (from old car - probably won't be used). I have a lot of the same questions, what do I need to get this to interface with the stock soundsystem w/ NAV and the AM/SAT button? And can I use the sharkfin antennae? Where is the wire for the shark fin... is it really in the trunk? -Brian