EXPREME exhaust manifold is now available for SR20 owners who want a performance upgraded from the genuine exhaust manifold. You can retain the genuine setup or any aftermarket bolt on turbo and no special modifications are needed. With the SR20DET the exhaust manifold was designed to be close from the exhaust port to the turbine. With the comparison test of there isometric prototype & the factory genuine manifold which also utilizes the same layout, it shows that the Tomei Expreme has succeeded in delivering an overall improved performance in both torque and power increase in areas like in the higher RPM range in which you were not able to utilize before. With Tomei’s extensive testing they have reached the conclusion that the normal design is superior as a total overall efficiency. So to develop an exhaust manifold similar with the design and setup as the factory manifold they were finally able to produce a product worthy to bear there name as a product that has the potential to deliver an overall increase in performance.