The aluminum cover is a lbs or two less than the 986 cover. I didn't weigh just the vert parts separately but Matt says 15lbs. I removed the motor, cables, transmissions, pushrods and associated hardware. I'm probably forgetting something else too. Here's a pic of my first round at lightning up my box
I go into more detail about my boxster on this thread
http://986forum.com/forums/show-tell-gallery/59449-woodys-build-thread.html#post496499