That is with an Autometer tach too. If I went off the stock dash unit I would probably be going 90 mph.
wind resistance, etc.. does not change my gear ratio and tire size. All you have to do is hit the number on the tach in 5th and do the math. Simple as that.
See my car at:
http://www.mustangworks.com/cgi-bin/moi-display.cgi?179