These dB killers are only fitting the Malparidos 2:1 Exhaust Systems for M8 Softail - M8 Touring and TwinCam Dyna and Touring.
The Race versions allows to increase the dB outcome of 7dB with the Medium version and of over 10dB plus with the XL version. Please note that the use of the Racing dB killers is not in line with the street legal requirements and homologations enforcement.