BD Exhaust Manifold Ram 3500/4500/5500 Cab & Chassis 6.7L Cummins 2013-2018BD's pulse manifold for the RAM Cab & Chassis vehicles is made from thicker walled high silicon ductile iron that is designed to resist thermal warping, plus withstand extreme temperatures and vibration. Engineered with state of the art modelling software to optimize pulse flow for optimal turbo spool and performance. Precision slip joint allow the manifold to expand and contract, which reduces cyclic thermal fatigue and greatly increases manifold