Anyone ever used 7/16 exhaust manifold studs

[BOBS90TURBO]

I had to tap in two 10mm exhaust manifold studs on the left side, and somehow they broke loose and caused a bad exhaust leak, so now I have to tap in a bigger bolt, the 12mm looks huge, but the 7/16 course thread studs look a little bigger than the 10mm and much smaller than the 12mm, the threads also looks much stronger, anyone ver done this or have any advise on what to do.

 

[idt512]

how about an 11mm? just to keep it all metric....

 

[BOBS90TURBO]

I dont think they make 11mm manifold studs, I can not find any, I looked everywhere