THIS NEW ATS 2-PIECE EXHAUST MANIFOLD CURES THE EXREME BACK PRESSURE PROBLEMS THAT ARE PRESENT IN THE #4 & #5 CLYINDER OF THE STOCK MANIFOLD! The ATS two piece pulse manifold for the Dodge Cummins application, with its pulse exhaust flow design, increases exhaust gas efficiency, helping to spool up the turbocharger sooner with less exhaust back-pressure. The pulse manifold design eliminates the problems that persist with the stock manifold - the shrinking and breaking of the manifolds. The stock manifolds can shrink as much as 3/8. This can cause manifold-cracking, gasket problems, and exhaust flow problems created by exhaust port misalignment. The ATS two-piece pulse manifold is cast of a much higher-grade material than the stock manifold, which will handle far more heat without being brittle.