At my car audio shop we have upgraded the sound system without modifying the car. We kept the factory head and replaced all speakers and added 4" mids in the doors in place of the pockets (without cutting)and added 2x10" subs in the trunk. With 6 speakers in the front and two subs and some good power this system sounds incrediable. If you want pics e-mail me and I will be happy to send them. This is an awesome car! Scott I recently went to a custom car stereo installer to have the speakers and amplifier upgraded. This installer is very professional and has had a lot of experience with exotics. Unfortunately, they had difficulties locating components and could not refer to a "body book" -- a resource w/ illustrated blow-ups of the entire car. Mine was also the first Z8 they had worked on. Currently, they are in contact with a source at BMW North America to obtain the info. they need so they can complete the install. Nonetheless, I thought I'd ask the members if they have had a custom install on their Z8 with which they were satisfied so I could have my installer contact them to exchange info. Side Note: They did comment that the Z8's fit and finish was definitely characteristic of being completely hand-built and unlike any other BMW they've worked on. Since these guys have taken apart and put back together many BMW's, Ferrari's, Lambo's, Porsche's, etc. they ought to know.