I contacted the good folks at Porsche about a diagram for my secondary air system. they would nice enough to send me a link to the "classic Porsche" part catalog. didn't know my 2001 was a "classic", but ok.
anyway. browsing through it it looks like it could be very handy trying to id parts etc...
if anyone is interested here is the link:
Porsche Genuine Parts Catalogue - Porsche Cars North America
about mid way down the page there is a "choose catalog" box. put in your model and year range and get the PDF catalog.