Don't have all the details on the install yet but will keep you guys posted. Thanks for the free air suggestion...I'll see what the installer thinks. By the way, I've had this installer do all the work on my previous cars (BMWs) and he is very good. Says he has done this upgrade before on several Mercedes models and the sound was incredible. Don't know the details on all the wiring yet but am pretty sure it's going to be complex. I do remember him saying something about a line level converter and RCA's and seemed very confident that the sound quality would only be slightly less using the stock head unit with the converter. Focal speakers would go in the front and the high end Orion amp would run both the speakers and the rear subs. He said something about creating some custom porting for the sub enclosure in the trunk. Quoted $2K for everything including labor....yikes!!!
I'm far from being an expert on this so I'll try to get some more detailed info and see what you guys think.

Trent, the WR is a '98 model that has a Baja Designs street legal kit. Love seeing the reaction of people as I come blasting down the road. Great way to get you to the track/trail without having to load up the bike.