So is there a fix for speedo inaccuracy in a stock S2K. If yes is it a permanent fix. Don't get me wrong I don't have much use for a speedo, too busy looking at the tach. It's just that I get such a warm feeling seeing 145MPH. I'd like to know if I'm really there.

 

I have determined that my speedo error is between 1% - 2% when stock gears were in. Digital speedometers have a lag time to "catch up" to the actually road speed. This lag time can vary from car to car and from MY to MY. To have accurately made any sort of statement, you would have needed to take the car up to a given engine speed and hold it for 2-3 seconds. As it would not be recommended to do this at redline, it is better to do this at say, 6000 rpm or maybe even as high as 7000 or 8000 (getting into risky territory here). If you can determine that at 6000 rpm (held for a few seconds) one car goes X mph, then when you do the same with another car, then you can compare the mph and extrapolate to redline and be more certain of any statements you make about that scenario.

 

Pretty much all cars have some sort of speedometer error to some extent or another. If you want to correct this error to ZERO, a Yellow Box will do this, however, the use of this device can be "abused" in a way to reduce the amount of miles put on a car and thus, would be illegal. And no it is not permanent due to the fact that it can be changed and can be removed.