Abstract: An exhaust system tuned during low RPM operation while the exhaust chamber retains its preset tuning for optimal high RPM operation. An exhaust controller according to an embodiment of the present invention receives an RPM signal from the engine and processes the signal to activate a solenoid which controls a valve that injects coolant water into the exhaust chamber. The injection of the water into the exhaust chamber has the effect of cooling the exhaust gases, thereby increasing the density of the exhaust charge in the chamber and slowing the exhaust pulse wave, thereby optimizing performance at relatively lower RPM levels.