I've been looking at those round gas tanks on the Go Karts USA site as a potential for a project. I believe they're made by Little BadAss, but not really sure. Anyhow, they show two models; one 7" long and one at 11" long. The 7" model is specified at 4" in diameter, but I don't see a diameter for the 11. Maybe I'm seeing things, but it appears the 11" model is a bit smaller in diameter. Anybody out there know if the diameter is smaller on the 11? Thanks.