The "header" allows for a more free flow of gasses through the motor.
Better charging and exhaust of the cylinders means more HP.
The motor has to suck in air/fuel mix,then pump out the burned exhaust,and
the less restriction in doing that means more power.
The "wheel-like things" are replacement cam drive pulleys,probably
undersized to use less HP for driving the valvetrain.(How that's supposed
to work,I don't know.)
Only a dyno test would show how much more power you achieve with these
A lot depends on how good the original setup was.
I suggest you try the header first and see how that goes.
The cam pulley mod is probably a job for someone with the right tools and
knowledge to insure the cam timing does not get altered.(possibly damaging
you valves and cylinder head.)
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