Shown with optional riser bung. These high performance manifolds are unique in design, that creates a high velocity airflow that increases torque, rpm, and horsepower over stock cast iron manifolds. We have experienced 40-50 foot pound of torque on bigh block 502, 415 horsepower motors, and 80 to 90 foot pounds of torque on engines up to 575 cubic inches.PowerFlow manifolds are water-jacketed, water surrounds each exhaust passage, including the ports to eliminate burnout. Black manifolds are hard anodized prior to powder coat, to ensure against corrosion.Big Block std. Stainless steel “S” pipe is unique in many ways. These pipes will fit many pre-existing port locations That are about crankshaft center line, and is widely used with swim step applications as well as V-Drives and Jet boats.the lower elbow is adjustable up & down with a 4" exhaust tip hose contention.3/4"npt fitting is used on front of pipe for thermostat housing that have (4) 1" hoses water to go to exhaust manifolds if needed click on (ADD BUNG). Shift bracket, ECM, or EFI brackets available as bolt on or welded to the risers.To order see powerflow accessories.The risers are highly polished stainless steel, and are designed for 4" exhaust tips. We offer a wide variety of riser pipe configurations to accommodate just about every application. Custom riser pipes can also be manufactured