Pre-built replacement header tanks for the model-4

I recall there are some issues with the supplied small poly tank on the model 4, which mounts behind the pilot seat. I was looking for a pre-built tank to save time, maybe a bit larger too and of metal???. Any good sources? What did you use and why? (or don't worry about the poly tank ??).
Thanks in advance
Roger

Kitfox makes an aluminum tank now. I replaced the original poly tank with a second poly tank, and then put in an aluminum tank because both the poly tanks leaked, and leaked badly.