So you are probably asking, "why would you want to add a sirius tuner to a car that has XM/Sirius built in?" Well... I already purchased a lifetime subscription to Sirius and it is linked to my SC-C1 Tuner. You can transfer ownership 3 times for a $50 fee but they will not let me transfer to this vehicle as it is sirius and XM. So, back to my dilemma, is there any way for me to add my SC-C1 to the stock radio in this car?
Don't know if there is a solution for this but it is looking like I am out of luck. Every model before 2009 had an external tuner and you could plug in an adapter. It looks as if the new Prius models have the tuner built into the stereo... still hoping for a suggestion though... may just have to replace the stereo.
I also have xm i connected to the audio in plug by glovebox works great anntenna is on dash in middle works o.k. semi next to you blocks signal here's a picture you can also buy antenna adapter for you xm or sirrus from best buy cost 16.00 plugs into back of radio
Just for reference... I did stumble upon a solution... it is not extremely elegent but it does exist. Kenwood KOS-A300 Factory Radio Upgrade System Add Kenwood gear to your factory stereo at Crutchfield.com