I think they do but stainless would be the ultimate. I just don't care for the coated headers . Never had luck with the coating not chipping off and then you have rust anyway.
So realistically My build plan is 400HP street , would TTI or Dougs be over kill or is it " to each his own ". I don't mind putting out the money if its called for but at my HP would it be like a status thing.
