It has been done successfully and there are few threads and videos out there of V12 Twin turbos running as well as supercharged:
http://www.e30zone.net/modules.php?n...ight=v12+turbo - super charged
http://www.youtube.com/watch?v=J_6OedKNUX8
Have a look here for picture of a pair of turbo manifolds:
http://forums.bimmerforums.com/forum...d.php?t=609152
Not seen any indepth build threads but there may be some out there
