It is for good reason that virtually every top professional engine builder relies on ARP Pro Series head studs for their all-out competition power plants. For openers, ARP uses a premium grade 8740 alloy that is rated far superior to “aircraft” quality.
These studs helped seal a very lightly leaking head gasket on my 6.7 cummins. I used GDP's one at a time method and couldn't be happier with the result.