Per the dictionary.....
http://www.merriam-webster.com/dictionary/header
Nothing about exhaust in there.........hmmmm
Then there is....
[ame="http://en.wikipedia.org/wiki/Exhaust_manifold"]Exhaust manifold - Wikipedia, the free encyclopedia[/ame]
Quote "For many engines, there are aftermarket tubular exhaust manifolds known as
headers in [ame="http://en.wikipedia.org/wiki/US_English"]American English - Wikipedia, the free encyclopedia[/ame], as [ame="http://en.wikipedia.org/wiki/Extractor_manifold"]Tuned exhaust - Wikipedia, the free encyclopedia[/ame] in British and [ame="http://en.wikipedia.org/wiki/Australian_English"]Australian English - Wikipedia, the free encyclopedia[/ame],
[1] and simply as "tubular manifolds" in [ame="http://en.wikipedia.org/wiki/UK_English"]British English - Wikipedia, the free encyclopedia[/ame].These consist of individual exhaust headpipes for each cylinder, which then usually converge into one tube called a
collector. Headers that do not have collectors are called '[ame="http://en.wikipedia.org/wiki/Zoomie_header"]Tuned exhaust - Wikipedia, the free encyclopedia[/ame]'."