It will be a bit of mucking around but I ultimately I want a 30L safari tank on my XT660R. Once it is out of warrenty I will take the fuel pump out of the tank and mount it in its own little chamber on top of the crank case. That way I can gravity feed to the pump and pump to the injectors. The tank they put out for the Suzuki DR650 almost fits but isn't wide enough to clear the radiator, so a radiator off another bike would probably work.

Shame that Safari Australia isn't stepping up to the challenge but they did say they would make a 30+ Litre tank if they had enough orders.

An XT660R with a 35L tank would be a Tenere killer...