Haha, well I had to disassemble my gauges and needles to install intelli-glow needles, so last time I had the needles off, I had someone with a stock car drive 65mph next to me with cruise on and I matched their speed with cruise on and then I replaced the needle at 65 mph and then I had them speed up to 70 and then down to 60 and stayed with them and checked to make sure my speedo was close and done.

I know it is not a perfect fix, but it is nice to know that at around 60-70 mph the speedo reads true :-)