I would agree with trying to wash out the tanks with fresh fuel, but I would not put fuel filters between the wing tanks and header tank. That is a gravity feed situation, and it doesn't take much to stop fuel flow when it's just gravity feed. I have had an unplanned off field landing because of this. After the header tank, the fuel pump is providing suction, and will have a much easier time getting fuel through a partially plugged filter in that location. And for that mater, the header tank is really a large gascolator, so it should stop most stuff coming through. Just my 2 cents worth, and worth every penny you paid for it! :-) JImChuk