Check out LC Engineering. They have a really popular header, I run one, and it allows you to bolt up that tube. BTW, the tube has nothing to do with your heater, it just takes exhaust and feeds the smog pump. But if you arent worried about smog stuff then you can just run block off plates on top off the header. Hope this helps.
it helps to know the year of your truck or at least tell us if its carbed or EFI. because the quote above is taking about one thing and i am talking about another. but Skyscraper is right your heating issue has nothing to do with your headers. the only thing there i can think of is your heat riser. are you having issues of overheating your engine?
