Yup I have the same car except not a gxp and 06 so it has the 3800 SC engine instead, Ive disconnected the battery many times, some of the major electrical mods Ive done to it was converting it to dual climate, factory navigation, xm radio and installing heads up display.
I got a program that has all the service info, procedures and schematics for all the systems.
Mine also has the monsoon system in it as well with the factory amp in the trunk and center dash speaker.
When you disconnect the battery just disconnect the negative first(prevents accidents from happening) and youll be good, if your observent you might notice different driving behavior for a first trip or so just while the computer is relearning the sensor data and stuff like that.
If you need anything else let us know or pm me, I know the whole car inside out and where everything is.
