If this is your first jet, I too recommend getting a single. especially if you are starting with a warbird. A single will save you a lots of $s when you crash it. Better yet, look at a training jet and better your chances of not crashing until you get a lot of experience. I personally don't like the filtered clunks. So much easier to clean an external filter and you need one between the fuel pump and the turbine anyway, … unless the turbine has the pump mounted in the turbine. Then they don't want any filter before the turbine because there is a filter under the cover too. O-Rings do not need sealer, unless there is a problem with the sealing surface. I am using a dubro tank in my Sprint. It is flimsy and has still held up well over the years. I personally have never used a pop bottle. But I have seen several out there and they seem to work. Only thing is they don't take full advantage of the space in smaller jets as well as a custom tank might. I go with whatever gives me the most fuel as there seldom seems to be enough.