True except when I did the research for my IM to make a new tank IM made a wooden test box and I found the custom tank maker and 10 units was the magic number. The. I found out about the existence of a larger filler pipe and cap and had one sent to me after the build . Just saying
After all of this I found out I could have done the tank in injection molded material for the same cost with even more fireproofing that an all aluminum unit