Tomei introduced the high efficiency 4-1 as against the STD 4-2-1. The exhaust efficency of the standard exhaust manifold is not perfect. But Tomei 4-1 type exhaust manifold has high efficency. You could see the change of dramatically driving feeling.

The complete equal length is good for the exhaust intervention but reduce the turbine performance and increase the exhaust resistance. Contrary to that, the not-equal length exhaust manifold can lead the efficiency of other cylinders. Tomei design the not-equal length.

We design not-equal length same as STD that is remained the boxer sound. The clear sound which got dry further by change to the diameter of the support pipe and the stainless steel quality of the material is pulled out and the good feeling could be obtained at the acceleration.