Since tubular steel exhaust manifolds typically have better flow, they are most often found on performance-oriented applications, like sports cars. However, there are a few automotive manufacturers out there that prefer using tubular manifolds on non-sport models as well (I'm looking at you Jeep!). This style exhaust manifold can be made from mild steel or stainless steel depending on which the car manufacturer preferred. As you can imagine, mild steel is cheaper to produce, but it won't last as long as a stainless steel exhaust manifold would. The steel tubing that the manifolds are constructed with is welded to the cylinder head flange, and at all of the points where the tubing intersects. Many tubular exhaust manifolds also have built in flex-pipes that allow the different areas of the manifold to flex independently with the temperature changes. Unfortunately, like the cast iron exhaust manifolds, tubular steel manifolds crack too.