GMC produces big trucks and big SUVs which equate to bigger fuel combustion and exhaust gases. To compliment this, GMC has dependable exhaust system that works to keep the exhaust gases in one direction, save fuel, silence the engine noise produced by engine combustion, and convert these gases into lesser harmful ones. As the fuel combustion occurs inside the engine, the exhaust system headed by the exhaust manifold collects gases.

The exhaust manifold is composed of connected at the exit passage of each cylinder. Usually made from cast or nodular iron, the exhaust manifold is designed according to the type and size of the engine and the number of cylinders. The exhaust gases in the form of hydrocarbons or the unburned fuel, carbon dioxide, sulfur dioxide, carbon monoxide, nitrogen oxides, phosphorus lead and other metals from each cylinder will merged into one pipe that will directly go to the catalytic converter.

The catalytic converter transforms these gases into water vapor and carbon dioxide. These would then go through several pipes and parts. The resonator and muffler, another part of the exhaust system, reduces the noise level produced by the combustion before the gases lead to the tail pipe and joins the air. All modern vehicles are equipped with oxygen sensor which measures the oxygen content of exhaust for fuel economy.

Like every part of the exhaust system, the exhaust manifold encounters its worst enemy, corrosion- in other words, rust. This reduces the life span of the manifold that could result to lesser gas mileage and leads to leaks if the situation worsen. To avoid these, proper maintenance is required for the maximum efficiency of the exhaust manifold and the rest of the system.