RE: Filling the tank with the cowl on
That is precisely my problem. I don't have any difficulties with filling the tank, I struggle to see when it is full. In my stick, I remove the back-pressure line and fit it to a small container. As soon as the fuel runs into the container, I know the tank is full. With the cowl I cannot get to the pressure line, and therefore cannot see when the tank is full.
The dubro filling valve works like a charm.