The most knowledge is on Pointedthree. Tons of technical information and diagnostic know how. :ylsmoke:
Benzworld has a lot of new G topics, tends to be more of the tuner and street version, but some old school as well. This was the main forum before pointedthree was created in 2003:bike_rider:
And of course we have this forum.:sombrero:
As suggested above, really good peeps across the boards