You can purchase the latest Outlook OEM/Factory Navigation/Stereo unit complete with the OEM GPS Antenna and the latest GM Nav Map Disc and full installation instructions (everything that you need) for about $700-$800 on eBay or from other online Car Audio dealers! Even with installation fees and possible programming this will be much less than the OEM-installed cost and you will have the identical system! Here is a link to one:
You will however need to order the $980 "Advanced Audio Package" for simple Plug & Play results, as the OEM NAV/Stereo unit uses the Amplifier and other connections that are included with the Advanced Audio Pkg. Someone correct me if I'm wrong, but in my search for info on this topic this is what I have found. You might also need the dealer to "program" the unit. Most dealers will do this for free or a nominal fee...do a search. You could always sell the OEM A-A Pkg. 6-Disc in-dash CD/MP3/AM/FM stereo on eBay to recoup some of the cost.
Most aftermarket Audio/Video/Nav source units are Double-DIN size and will drop into the Factory location with little to zero modifications! You have a lot more choices with an aftermarket unit...you can add Hands-Free Bluetooth, HD Radio Tuners, XM/Sirius Tuners, Direct On-Screen iPod Control, USB Device compatibility...the list goes on and on. Even with installation fees, an aftermarket unit with superior features should be quite a bit less than the OEM cost of $3,025 (You must have both the OEM DVD/Navigation Advanced Audio Package $685 + DVD NAV System $2,340!!!)
There are also several aftermarket interfaces/adapters that allow you to use your factory Audio/Nav Steering Wheels buttons to control the functions on the aftermarket Nav/Stereo unit! These will also allow you to add other aftermarket A/V equipment such as Amplifiers, Subwoofers, Equalizers, 5.1 Surround Sound Processors, etc. Check out products by PAC/Pacific Accessory Corporation at www.pac-audio.com
, Peripheral Electronics http://www.peripheralelectronics.com
, SoundGate http://www.soundgate.com
, PIE/Precision Interface Electronics www.pie.net
, the JL Audio Cleansweep www.jlaudio.com
, the Rockford-Fosgate 360.2 www.rockfordfosgate.com
, MTX re-Q5, etc. Here's a link to most that are available:
Hope this helps!