Step1: Remove the seat and left panel
Step2: Identify the stock WR250R speedo cable. Make sure to get the one towards the front of the bike as the rear one is the power for the tail light.
Step3: Connect the SpeedoDRD
Step4: Tuck the SpeedoDRD away and zip tie the cable
Step5: I went for a ride with a GPS to see the difference in speed. GPS said 60MPH, speedo said 70MPH. GPS was 51.8 and speedo was 60MPH.
Step6: Using their online calculator for setup I saw I should be using anywhere from a -13.7% to a -14.3% adjustment. I chose to use a -14.0% adjustment and am now within 0.5MPH on the speedo which is good enough for me since the stock gauge doesn't show tenths.
Step7: Follow the Detailed Calibration Instructions. I suggest reading them at least once before starting. I missed a step and had to start over on my calibrations. It sounds more complicated than it is to change, but once I figure out the procedure, I was able to make adjustments very quickly.
Step8: Enjoy having an accurate speedometer!