What's happening when you try to set the ratios? Here's the instructions btw: A. Select the [Prg] menu option, press and hold a button for 2 seconds. [gr.1] is displayed. B. Drive the vehicle in 1st gear at a steady speed. Quick press a button, LEDs will blink to indicate 1st gear ratio is saved. [gr.2] will automatically be displayed after the 1st gear ratio is set. C. Drive the vehicle in 2nd gear at a steady speed. Quick press a button, LEDs will blink to indicate 2nd gear ratio is saved. [gr.3] will automatically be displayed after the 2nd gear ratio is set. D. Repeat procedure for each remaining gears. [gr.4][gr.5][gr.6] Please note: Driving speed only needs to be steady for each gear and does not need to be close to the red line. For example 5th and 6th gears would be driven at a safe and legal speed (50-70MPH) while corresponding lower gears would be driven at slower steady speeds.

Depends on the devices and if they are competing for the same signal / readings.

No.

@@VampyreX13 awesome, thank you!

The RPMs are correct. If you check the video description, I did add a note that I realized that after the fact. I have repositioned the shift light so I can actually see the LED screen while driving and it's spot-on with the car's tachometer.

100% yes. It will come on just before your target RPM to give you enough time to react. I have mine set to 7200, but I'm about to change it to 6800 since there isn't any power gain going above that RPM.