I'm planning on changing the gear ratio in my car, but I'm looking for a tuner that will help me keep my speedometer correct. Does anyone have any ideas or suggestions as to what I should get or where to buy it? Thanks if anyone can help me out, I need it asap.

 

Changin gears won't affect speedo. The signal for that is established through the ABS module from the wheel speed sensors. So only wheel/tire overall rolling circumference will affect speedo.