I know you're asking about headers, but I'm gonna offer a different suggestion, one which you're probably not interested in hearing. Headers are a performance component designed more so for mid to upper rpm power & performance. It's also a nice dress up component but it's been my experience that headers on a regular, daily driven vehicle isn't really beneficial.
Headers are designed to flow a lot of exhaust. However, at low rpms such as those seen 90% of the time on a daily driver, headers provide no real performance benefits over a pair of cast manifolds. The good old fashion pair of cast iron exhaust manifolds flows more than enough at normal highway rpms. So the question for you is, do you really need headers?
The factory cast manifolds aren't going to win you any awards or cause your friends to drool, but they are dependable, cheap and last almost forever. They also don't heat soak everything under the hood. Unless you're building something healthy, I would recommend you save your money and just use the factory manifolds.
Ed