Header explanation? Please

Bill, all I can say ( being of the hillbilly mindset myself ) is I know they work for power. I had a 77 Blazer w/ 30? 2 bbl/4spd granny 1st gear/ 3.?? ( highway ) rear end and had to downshift up steep hills. Had headers installed and zoom zoom up the hills. I would have them on the 65 Dart if they wern't so expensive for the pre 67 A-bodies.