I added an additional 5 liters of fuel to my bike by fitting and plumbing in a 5 liter ACERBIS number board tank. I have just returned from a 3 day trip and it work like a bomb.
Can you show us some pics of the plumbing. I'm interested at a similar set-up for my new TE 630. How did you connet to the tank. I see a hose comming out the acerbis tank but cannot see how it is link to the main tank.