Info here http://www.z4-forum.com/forum/viewtopic.php?f=2&t=8793 
pdavis444 said:Hi, Just bought a 03 z4, Would like to know, if to replace my ripped convertible top, do you have to remove the whole top assembly from the car first? Thanks, I really enjoy reading the post and advice that all of you give.
Z4Helper said:Request for:
How do you install a HID Conversion Kit for a Z4 06 3.0i?
Which kits are safe?
Will the error message show up on your dash if you do this?
Thanks.