SpeedoDRD 
Speedometer "Digital ReCalibration Device"
 

The smallest electronic speedometer/odometer calibration device in the world.

• Priced below any competing product on the market
• Easier to setup than any other device on the market
• Allows speedometer correction in 0.1% steps, up to 99.9% + or -
• Saves max speed, which can be recalled to your stock speedometer gauge
• Simple plug-in installation for many vehicles using factory OEM connectors
• Works for any 3 wire Hall Effect Sensor, or 2 wire Ground Switch Sensors
• Works for vehicles which display MPH or KPH
• Ability to convert MPH to KPH, or KPH to MPH
• Available with frequency multiplier & divider for gauge cluster or transmission swaps.**
• Weather proof design to protect against the elements
• 3 year product replacement warranty
• Made in the USA

Is this device compatible with a fuel programmer or other devices...
Yes, make sure to connect the other device directly to the speed sensor, then connect the SpeedoDRD; The SpeedoDRD should be the last device in the chain of devices, so it connects to the main harness which goes to the ECU or Gauge Cluster.

Why would you need a Speedometer/Odometer Calibrator...
Many vehicles (especially motorcycles) come from the factory inaccurate, sometimes as high as 10% off. Also, modifications such as tire size changes or gearing modifications can cause significant speedometer inaccuracies. Thus the speedometer calibration device is used in series with the speed sensor in order to correct the signal before it reaches your vehicles ECU computer. SpeedoDRD works for vehicles which are manufactured with electronic needle or digital readout speedometers, with 2 wire or 3 wire speed sensors.

How accurate is 0.1% correction steps?
If you were traveling 60mph (or 60kph), 0.1% of that would be 0.06mph (or 0.06kph)
If you were traveling 200mph (or 200kph), 0.1% of that would be 0.2mph (or 0.2kph)
If you were traveling 300mph (or 300kph), 0.1% of that would be 0.3mph (or 0.3kph)
Thus correction steps of 0.1% are more than enough to get your speedometer more accurate than your gauge cluster is capable of displaying.