if you have not already started on the install - call these guys 770.429.1600
http://www.sound-sensations.com/
sound sensations (in Marietta GA) - they did my 2001 E55 with a killer setup for the avic z1 - i can send pics - ask for Mark Vickers and tell him Derek sent you and he will hook you up - been using these guys for years for anything in the car - they are on the cutting edge and you have seeen many of thier designs and custom stereo stuff in Hip hop Videos.