Final answer:
Cracks in an exhaust system are commonly found in the exhaust manifold, at the joints, and around the muffler and catalytic converter due to heat, stress, vibration, and corrosion.
Step-by-step explanation:
The most common places to find cracks in an exhaust system are typically the areas exposed to high levels of heat and stress. These areas include the exhaust manifold, the joints where different sections of the system meet, and the areas around the muffler and the catalytic converter. Over time, the constant heating and cooling cycles can cause the metal to fatigue, leading to cracks. Additionally, the vibration of the engine and vehicle movement can contribute to the formation of cracks, especially if the exhaust system's hangers or mounts are worn or defective. Road debris and corrosion due to exposure to the elements can also cause the exhaust pipes or components to weaken and crack.