[QUOTE=JoelWisman]There is no diagram of the system I'm aware of on the publically available service DVD, or the dealer only RSD.
There is however a great video complete with animations at BMW university, a web site that's only available to BMW employees. I have no idea why BMW keeps stuff like this secret, but they do.
In any case, YES, at the least the USA variant of the F800GS does have what is commonly known as a "second air" system.
Thank you Joel for answering all my curiosities about this in one place, I appreciate it.
I had wondered about this ever since leafing through my new Haynes manual, and thinking to my self that I'd seen secondary air injection systems on other bikes, but didn't see any sign of the hardware I was familiar with on my GS. Glad to know where it is & how it works.