I installed the ADV tank over the weekend. It took me about half an hour tops.
It fits nicely and the aluminum rack will come in handy to mount my Motofizz bag.
The supplied (and online) instructions are excellent.
The only thing I'm not crazy about is the venting hose that attaches to the filler cap. I had something identical on my KLR's plastic IMS tank, in the end I ended up removing it and mounting this vent doodad in the pic below.
Do youse see any reason I should keep a venting hose on the filler cap, that basically goes back under the seat and ties into the bike's venting hose that I disconnected from the tank. (My bike does not have the evap. canister).
My riding season begins this week. I will fill the ADV tank at the gas pump and snap a pic of its capacity. And then let the riding begin. I'll update this thread with my mileage range. I'm taking my GS to Colorado this summer for some touring and D-S exploration, so that's where the extra fuel will come in handy.
p.s. will post pics of the tank on the bike once the bike is back in the garage.