I Said Never Again, I Bought Hedman Headers... Again.

I think because I was taught to true/fair the mating surface by weld/file, they fit flat against the head to start with, twisting separate tubes wasn't necessary.
I was always able to use the flange gaskets supplied, or Mr Gskt replacements.
Never had leaks or needed Remflex.
My mentor wouldn't allow any header to leave with a leak or rattle.
I think I had to re-do 6 of the first 8 sets I installed, - had my *** kicked .
Learned to weld, lol