Abstract: A resonant frequency adjustor for mounting onto an exhaust pipe of an exhaust system of a vehicle adjusts the resonant frequency(s) of the exhaust pipe to minimize or control vibration transmitted to the vehicle and/or to tune the sound emitted by the exhaust system. The resonant frequency adjustor includes a base mounted to the exhaust pipe, an isolator attached to the base, a stud attached to and extending from the isolator, and a mass located on the stud. A gross adjustment of the vibration of the exhaust pipe may be achieved by varying the location of the resonant frequency adjustor on the exhaust pipe. A fine adjustment of the vibration of the exhaust pipe may be accomplished by adjusting the position of the mass on the stud.