Even if the car body is reinforced and made more rigid, road surface input through the tires and load shifts during cornering make the entire body act like a spring, causing the occurrence of micro vibrations. The performance damper acts to control the transmission of micro vibrations to the body. During circuit driving, micro vibrations from the car body are transmitted through the steering system to the driver, resulting too often in unnecessary steering corrections. With the performance damper installed, however these micro vibrations are eliminated and excessive steering wheel handling is no longer needed, resulting in more stable handling. Also, in normal driving, the micro vibrations are eliminated, as well providing a much more enjoyable and comfortable ride.