On my new '07 Silverado, it comes with an XM/Onstar/Handsfree Phone antenna mounted on the roof. Does anyone know of a way to tie the XM add-on to this antenna instead of running a new antenna?

Thanks.

The factory xm tuner is behiind the glovebox i beleive. You'll have to remove the plastic piece around the antenna end. After that you can plug it into the pioneer xm tuner. then just mount the pioneer tuner where the factory tuner was.

Thanks for the help!

And it should just plug right in? No wire modifications needed?

And would this work with the XMNAV version as well?

No wire modification needed if your stock satellite antenna uses a FARKA connector. Like cntrylvr said, just remove the plastic piece around the connector. Im not sure if it varies from car maker to car maker, but isnt the plastic piece pink colored?

Not in gms it's kind of an old computer beige color. once that piece is off you'll have no problem plugging it into either the navtraffic tuner or the reg tuner.

Do you guys know if this will work for Sirius as well, or just XM?

It might work, depending on where you are. The xm and sirius antennas work on each other here in jersey, new york area. They don't though out west.