There are pro's and con's for headers.
Some like them, others dont.
The problems that i have faced with a header on my 6 cyl was that the collector is in a spot that the front driveshaft always wants to bash when i'm in a flexed situation.
I have had that happen more than once, and the fact that all the more performance that you can gain from a header, you are further ahead to keep a stock manifold, and get a custom larger diameter tube made for the head pipe.
I have a complete custom 2.75" exhaust from the maifold to the tail pipe, with a cat, and a bullet muffler, all stainless, everybody asks me what kind of header i am running....NONE...stock manifold.