A beautifully made original 1925 Norton brochure, in Dutch.
The caption to the Model 18 reads that the engine can be tuned to do a 100 MPH without fear of breaking it. Further, special 'go-faster' goodies like narrow mudguards and a smaller petrol tank could be specified.
Interestingly, the excellent Webb forks could be replaced at the factory by the inferior Druid type forks while a gearbox with normal ratios could be fitted to replace the close ratio gearbox that came as standard!