Yep and trying to figure gearing from tach, speedo, tire height is only accurate IF the computer has been reset for the new gears, and you use actual measured rolling radius of the tires instead of manufacturers advertised diameter.

For instance if you were to take a 3.23 geared car and throw a 3.42 rear under it without flashing the 'puter, drive it down the road logging the speedo and tach and you'd calculate that it has 3.23 gears. Now if you used a radar gun to capture actual speed versus the tach readings you'd then calculate that it has 3.42 gears.