So I bought my first mustang and it is a 1998 mustang cobra. The speedometer is completely off and it says im going about 100 when im only doing about 65 on the highway. I have found out that there is either a performance chip or a downloaded program in the ECU. There is also 4:10 gears in the car as well. I need to fix this and I wanted to come on here and ask and find out which tuner everyone thinks would be the best to tune the car for performance and get the speedometer to the right calibration. Thanks!