The exhaust manifold is the key component in the exhaust system on a vehicle. It is responsible for collecting the exhaust gas from the engine's cylinder heads and sending it down to the exhaust pipe. At the same time, it prevents any toxic exhaust fumes from leaking into the passenger area of the vehicle. Exhaust manifolds come in two main design styles, commonly referred to as four-into-one and four-into-two exhaust manifolds. Most exhaust manifolds are made from cast iron, but aftermarket versions are often made from welded tubular steel. A damaged exhaust manifold should be replaced immediately, and car owners in the market for one need to know which features to pay attention to in order to find the right one.