I used a 2oz. header tank ontop of a custom fibeglass tank I made for right behind the rear cockpit former. I shaped a block of foam into the triangular shape and then glassed it. Worked well and could hold tons of fuel for the .91, something around 20-25 ounces, which is a lot. I ended up using the Robart air up,spring down 510 units for retracts. They fit pretty well, but there is nothing "ARF" about this model.