I have the Z110bt installed in my X but I originally had the OEM nav. In my case there were no speaker wires to tap into at the front. I believe the radio tuner in the back has the 4 channel out going to the factory amp. You can probably just tap into those so you can keep the factory amp and all 10 channels.

Here is my install link
http://www.xoutpost.com/electronics/...tall-pics.html