Changing rear gears

[Nickerson]

I am changing my rear differential ring and pinion to 3:54.1 ratio in my 2006 Viper. What do I have to change to keep the speedometer correct?
Thank you

 

[MoparMap]

The speedometer runs off of the wheel speed sensors, so I believe it should auto adjust without you having to do anything. It just cares how fast the wheels are turning, not the transmission like earlier cars.

 

[redtanrt10]

Yep, you don't need a calibration box on your Gen 3.