Hmmm...based on this feedback, I think I need to bribe Marco to allow me to come over to his pad for a "good Lookin' at". As far as the fumes in the cab go...maybe they are migrating from other not-so-sealed up places. I do know the manifold is leaking at that spot Subzali also described.
Like most things at this level, nothing is as easy as "remove and replace". If I can easily get that leak repaired with everything still on the truck that's great. doubtful, but would be great. the reality is that I have that header, and if everyone said DO IT!!!! it's a no brainer. I think I need to determine the root issue - I don't think there are any performance gains that would coerce me to go for it.
I wouldn't mind freeing up some space under the hood to put a PS pump (instead of an smog pump). Decisions, decisions...Oh...and money, money.