does any one know why this is needed with 07 that already has a rear view camera. couldnt the camera harness be spliced?

 

I believe it is possible and recall a thread with info on this. Try searching through the Audio section.
The Navtool (Dom's, whatever) is Plug n Play and a lot cleaner, IMO.
Of course, the optimum is to relocate the OEM screen to the cubbies and install a true VGA screen!

 

you can splice it and have the camera come on while driving but it won't get the signal right for the navi screen and can damage the monitor. The Stock navi screen has a low resolution and a low refresh rate compared to 99% of all the dvd players on the market. Putting in the wrong format signal (to fast of a refresh rate or to high of a resolution) can damage the LCD. Dom's helps to minimize that as it converts it into RGB and tones down the refresh rate among other things.

Also if you have an 07, you can have the benefit of having 2 video inputs vs the guys with the 04-06 w/o the camera that have to dedicate one to a camera and the other to their source of choice.

 

Thanks for the info guys