Thanks for the detailed report on your fuel tank mods, that should fix it! Good to see some alternatives to replacing or weld repairs of the tanks. I like the kitchen chopping boards under the tanks. I have one under the tail of my M3W to help prevent damage to the skin if the rear wheel drops off a kerb, they are very useful and cheap.
Most of the tank leaks I have heard of have been from cracks starting in the bend corners of the forward attachment brackets, a smaller number have been from bad welds in the seams on the edges of the tanks. I would say that the cracks in the forward brackets are from fatigue caused by movement of the tank, the crack then propagates through the weld and into the tank. No doubt this crack propagation route is not helped by the less than perfect welding but I don't think the leaks are just down to bad welds, or they would be happening all over the tank rather than a specific point. Leaking tanks (at the forward brackets) seem to be on cars that have done some miles, they don't happen from new, which also suggests movement and fatigue is the main cause I would think?
