421 Exhaust Manifold - Civic, Integra DC2R/DB8R,EK9

4-2-1 design. Includes all required hardware. Developed in response to demand for a balance between peak power and torque. Spoon implemented various combinations of pipe diameter, assembly rotation, and other similar factors in exhaustive engine-bench, flow-bench, and actual-driving tests. The power and torque were successfully balanced and using slightly uneven lengths for pipes, further reducing considerable weight.