It can be said that the Honda NA engine has relatively low low-speed torque and has a superior 4-2-1 layout. Therefore, it is recommended from the test and experience to combine the exhaust manifold and the genuine 2in1. All spoon exhaust manifolds use the foul insert method, which has no step with the port, and the TIG welding method, which is a skillful assembly technique. By reducing the nose, it contributes to excellent handling and also has secondary effects.