These 60mm throttle bodies are designed to replace the original equipment units on Datsun 280Z and ZX models. Dynamometer tests have shown improvements in torque and horsepower in the mid and higher engine RPM ranges on otherwise stock engines. We do recommend minor modifications to the stock inlet manifolds to maximize the performance potential of these units. When used in conjunction with other engine modifications these “Big Throat” throttle bodies will show substantial power increases. When installing the Datsun throttle body 202027, it is necessary to transfer the by-pass screw and spring from the stock unit.