Can you buy one header?

PoisonDart74 said
^No, street torque is all about 1,000 to 3,500rpm. Manifolds are perfect for this. Headers are all about high RPM scavenging. Quit trying to half-*** it, save your money take your chances. These cars are toys, and you've got to pay to play.

Supporting documents you want?

http://www.moparmusclemagazine.com/...0307_mopar_crate_engine_exhaust/photo_17.html

Bam. Have a great day.

1000rpm? are you serious? most any torque converter made for anything that is not a huge diesel will stall about twice than that.

Since you want documentation.
http://www.moparts.org/Tech/Archive/exhaust/9.html if thats not a big enough difference at 3500rpm i dont know what is.