I purchased the Rough Country calibrator and completed the install today. It was very easy and took approximately 5 minutes. I now want to check for accuracy. What app do you recommend to check and see how accurate your speedo is?
Spot on L6A. You're going to the island...I would think you could pretty much use any "speedometer" related app on your smartphone. I can't remember what I've used in the past, but pretty much, any of them would be just fine for reference or comparison purposes. Google maps seems to have this feature now as well.
Check your speed - Google Maps Help
The addition of a speedometer in your navigation shows you how fast you're driving on the road. Important: Speedometers shown in the Google Maps app are for informational use only. Make susupport.google.com