You can program it way off, so it reads 50mph when you're really going 100mph; therefore, making the odometer turn the mileage over slower; therefore, making it read less mileage than the actual amount of mileage you covered. You'll be half of the actual accurate mileage. You're bike reads 5,000miles when it may actually have 10,000 miles on it. That's how you can use the speedohealer to derestrict the top end of the motorcycle too. I know a guy that has his ZX12 and ZX14 derestricted by doing it like that and he uses GPS for accurate speed reading. His mileage is WAY off on his bikes.