Intake and exhaust manifold gaskets work together to seal the join between the manifolds and the cylinder head. The intake manifold gasket seals the intake manifold so air travels directly into the cylinders. The exhaust manifold gasket keeps unsilenced exhaust gasses from leaking out. Both kinds of gaskets can be made from a variety of materials including cork, paper or metal. There are even plastic intake manifold gaskets. Regardless of what the gaskets are made out of, if the manifolds have to be removed, the gaskets will need to be replaced to prevent leaks. Leaking intake manifold gaskets can cause poor running and leaking exhaust manifold gaskets - as well as sounding terrible can cause harmful exhaust gasses to leak into the cabin.