The XL7 navi unit will only work in the XL7. It is tied into the canbus (LAN) system and will theft lock if it does not receive the "alls OK" signal from the BCM and ECM. The navi unit aslso requires an external amplifier to work correctly and the eq is tuned specifically for the XL7.
Then there's the price...
Navi radio $4318 CDN
Navi Antenna $116
Navi dvd disc $502
As suggested by DC-IT, it would be better to install an aftermarket nav unit