Ok so may be we all know what a muffler is but what constitutes a header? From my youth I remember a big shiny metal tube mounted underneith the car and visable 'cause it was under the rocker panels. But what is a header really?

 

replaces the exhaust manifold and turns it from a plenum into a single tube for each cylinder that goes into a larger collector downstream.

 

It's like longer tubes for better flow.

 

the exhaust wwants to be able to flow out of the engine fast and easy. but the stock header (or manifold) is often restricted with small pipesor collectors. by buying an after market header it lets the air flow through with bigger pipes and collectors.

 

Thanks guys...got it.