The part of the exhaust system that is fastened to the cylinder head.
Poppet valves in the cylinder head that control the flow of exhaust from the engine.
A compound or substance that can speed up or slow down the reaction of other substances without being consumed itself. In a catalyst converter, special materials platinum or palladium and rhodium in parentheses are used to promote combustion of an burned hydrocarbons and reduce carbon monoxide and nitrogen oxides in the exhaust gases.