On my downtown 300 2011, from break in to 20,000 Km.s upon changing the rear tire while removing the exhaust , a washer dropped out the hole was 1/2 the size of the pipe, so must have been the RPM restrickor, on my frost -Yager 2009 did not see anything on it , on my Piaggio B V 350 the manual says a electronic restrictor cut in at 85 miles per hour, going down hill I have passed 100 MPH and it did not drag it back with the motor so it must cut off the torque at 85 MPH