How do headers improve the car/engine? Do vehicles have stock headers and we add bigger ones?

 

They improve performance if that what you are implying.

 

If its on an Si, its just one header. Any 4 cyl. And they do improve performance. I think that they just allow more airflow from the intake. Im probably not exactly right on that, just what I think.

 

Thanks 2000 LoW reD Si. I appreciate your answers. Thanks Remmy.

 

It improves the flow of exhaust from the engine, they are better than stock manifolds, and are best accompanied with a cat back exhaust and a high flow cat-converter, again, I'm not gonna try to sound like a know it all, just gonna add my two cents where I can.

 

The thing I dont like is when you get them they are all nice and pretty then you put them on and drive and they turn blue.

 

Where do the headers connect to? Are they attached to the catilic converter? Do Civics SI have two catilic converters?

 

Yes it is attached to the catalitic converter and there is only one. The other thing you are probably seeing is the resonator.. But a header is worthless if not accompanied by a test pipe/highflow cat and a catback exhaust system.. holla

 

mine isnt blue

 

whats the difference between a Axleback and a catback?