KAWASAKI ZEPHYR1100 SESMIC-3 STAINLESS ALUMINIUM ALLOY EXHAUST SYSTEM Over Racing's Race Proven technology is used to great effect, to increase the already impressive mid range torque and BHP to a new level. A sweet mellow exhaust note is just an added bonus! The system is constructed with stainless steel pipe, aluminium can, and stainless steel tail pipe, in a 4 into 1 configuration.