Headers...what do they do exactly?

[Panzer]

What exactly do aftermarket headers do? I see one of these performance shops selling headers and a "high flow" catalic converter for my car. I'm looking for things that will increase low end and mid-range torque for city driving. Not sure if this will do it though.8D

[stickshift]

Headers replace the exhaust manifold and the downpipe and they are designed to allow the exhaust pulses from each cylinder escape without interfering with each other on the way out.
There are two kinds of headers: 4-2-1 and 4-1. 4-2-1 headers have four pipes coming off the cylinder head. Those four merge into two pipes, and those merge into one pipe, which then leads out to the back of the car.
4-1 headers have the four pipes coming off the engine, and they merge straight into one pipe.
I believe that 4-2-1 headers are better for low to midrange torque, while 4-1s sacrifice some low to midrange power for high end breathing.
The 4-2-1s are probably your best bet, in this case.

[majikTib]

http://webhome.idirect.com/~trini/car/muffler.html

I find this to be pretty helpful. I believe it's the correct site. I HIGHLY suggest you copy and paste it into Word and change the color of the text and the format so it's easier to read.