Re: HOW to Test Speedometer
It's gunna show 299, but you won't be going anywhere near that fast. Use a GPS, or buzz a cop. That's the best way to get your actual speed.
Disclaimer: the cops gunna be pretty offended when he tells you how fast you were actually going.
Speedo healers can be used to correct the speed, but will throw off the mileage. You get one or the other.