Look, I'm not trying to start s***, but what do you mean "this is a weak spot"? How do you KNOW one of these will crack? Sure, that location isn't as strong as it COULD be, but I don't see it being as big an issue as you say. There are several ways of showing this that all involve stress analyses, how much boost you're running, the weight and interior surface area of the manifold and the properties of the weld material, etc. I don't see these manifolds failing given the conditions in which they are going to be run.honestly yes from my experiance.. this is a week spot.. what happens when one of these cracks? will you hold full responsability? jb weld no thanks this is a trick used yes.. but i would not use it in a daily driver.. where it meets fuel continuously.. if it manages a way to get sucked in to the motor and destroys my valve and piston no thanks.. this will cause air pockets i cant even port it out due to unknown thickness of runner.. i see my self filling in the gap tig welded and putting new injector bungs..
Regarding JB weld I had some in my 626 manifold (VTCS delete) on my daily-driver turbocharged Protege for over 2 years of 10 psi and not a single problem.
The point is, you bought a manifold that was designed and hand made from the ground up for reasonable production numbers by a few individuals. This is not a one-off manifold that took 1000 hours of work to complete, nor is this something mass produced by robots in a factory in Japan...