Sorry to ask such stupid questions... but could you all explain to me the purpose of headers/collectors/y pipes etc. basically the aftermarket performance parts of the exhaust system?

I want to start learning a lot of the performance parts so i'm just starting and don't know too much. Gotta start somewhere i guess

 

Header: Gearhead name for an exhaust manifold made from thin steel tubing, one "primary" tube for each exhaust port.

Collector: Where the primary tubes come together. Most 3rd gen headers are what are called "shorty" headers, where the primary tubes are relative short so that the collector is beside the engine instead of "long tube" headers where the collector is under the car. Shorties offer better ground clearance and allow the exhaust to be routed the same way as the factory did. Emissions legal 3rd gen headers are all shorties.

Y-pipe: On a "V" style engine, each side has a set of primary tubes and a collector. From the collector, a single tube routes each side to one point, where they are joined in a "Y" to a single pipe. Most 3rd gens have that "Y" before the catalytic converter, some higher performance versions came from the factory with a cat for each side, and the "Y" is after the cats.

Tubular headers offer less restriction and therefore more power than the factory cast iron manifolds. The rest is just routing and emissions related.