Speedo too FAST!

One of the crappy drawbacks to buying a car you know nothing about, is not knowing what previous owner did to car. As I have spent the last few weeks focusing on getting the car looking right, now its time to get it running right. One of the first things is my speedo is wayyyyy off. I have to do 20+ on the highway and seem to be going 1.3 miles for every real mile. Not sure where to even start? Maybe it had 4.10's and changed back to something stock and left the speedo at 4.10's????

Where should I even begin

Xcal tuner. I thing you can adjust for gear ratio, you just need to figure out what ratio is currently in it. I recall changing a transmission speed sensor on my 94 gt when i did the gears. Not sure if the manual has that or if only the automatic did. The speed sensor is about a ten minute job, but we are still left with not know what the current ratio is??

Just do it the old fashion way, jack the car up, spin the tires and count =]