Hey bro sad to see that
It may be that nuts are locking down on the stud instead of squeezing and sealing the exhaust gasket.
Try to back the nut off if it was too tight it may pull the stud.
On a capped nut I am careful not to Let the nut tighten on the stud but tighten on the exhaust flange.
Hope this helps my friend.
The header flange/manifold is made of aluminum. Bob Carpenter set it up like that kind of like sport bike with stainless steel springs as retainers. The stainless header runners just slip over the custum header flange/manifold. When I get back to Illinois I'll look at the 3 sets I have to see if my newest set are Identical to the original style
I believe he made some suttle changes .
Oh and I'm not talking about the spaghetti snake leg burner pipes