False, regearing will absolutely throw your speedo off. Mine was off until I used procal to adjust for my gears

 

No it won't. I have a Hypertech and can set the gears at whatever I want and as long as the tire size are programed the speed is correct. Get your facts right. The gears don't affect the speedometer reading. Those sensers are reading the distance your tires are traveling not how fast your driveshafts are spinning regardless of differential gears or how your TC is geared. Did you change tire size at the same time as gears?

 

Nope did tires before the gears and it was calibrated for 34 and 3/4 inch tires and 3.21 gears an my speedo was off. I then re calibrated for 4.56 and it made it correct again...why would you be able to program the gear ratio if it did nothing?