I may be wrong but I just set mine to near the recorded reading of torque resistance. I'm thinking slightly less is better as mine now has a tiny bit of whine. BTW, take note the axles need to be near level for this reading. Also, it was no where near the 180Nm mentioned.

For the speedometer error, I just did a test using GPS on my cell phone and got an idea of the error. Switching from the 3.07 to 2.47 caused approximately a 15 mph difference at 70. Of course, how much you focus on this will depend on the strictness of law enforcement in your area. As long as you aren't racing past the flow of traffic, they tend to be fairly tolerant in Texas. Eventually, I would like to do some research and find out the components on the cluster that calibrate this. It's probably something simple.

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Sam

84 300SD 350K+ miles ( Blue Belle )