I have a Sigma on my ZX-10R that is dead accurate up to about 150 mph then is starts reading erraticly. The factory speedo stop reading at 189 mph. For the record, my factory speedo is optomistic by about 7%.
As Rodney Dangerfield said, "Buells don't get no respect." The Harley guys won't claim them as Harleys. The sportbike guys don't think they are a sportbike.