There was a class action suit against Honda cars years back for optimistic speedometer/odometers that read to high. It involved a warranty claim. The defendents won. Most Japenese motorcycles used to read 3 to five mph faster than they were traveling. I think they are better today. My Harleys were more accurate. If i showed the difference on gps they usually dismissed this. OK. Cannot make them drink the water.
Directions ? That's only the Manufacturer's opinion of the way this should be assembled.