Speedo calibration, H0101, H0102, H0104, am I understanding it right?

[endo]

I have a 2004 GMC Sierra 1/2 ton 4wd 5.3/4L60E with a 12587603 OS. I'm trying to get a handle on these three parameters to get my speedo calibrated correctly:

H0101 VSS pulses/km
H0102 VSS pulses/rev
H0104 Trans output shaft revs/km

Does H0101 only control the speedometer's analog position, and H0104 control everything else, including transmission parameters, the odometer, and trip computer?

I had a Hypertech before EFILive. It set H0101 for my 33" tires, but left H0104 alone. It increased H0101 by about 4%.

When I pass those "your speed is XX MPH" roadside radar signs, the speedometer reading is perfect. But against a Garmin GPS on a 30 mile drive, my mileage is 3.5% off (truck is recording fewer miles than GPS). Google maps calculated distance is very close to the GPS.

So my thought is that H0101 is the speedometer needle correction, and H0104 is used for everything else. H0102*H0101 was equal to H0104 on the stock tune.

I think I need to adjust H0104 by 4% so that everything lines up again. (will do this by setting H0101 back to stock, and then using EFILive speedo calculator to update all parameters in one fell swoop).

Thanks for any suggestions.

[SSpdDmon]

Measure tire height - don't go by assumed calculation. Tire growth may occur at higher speeds, but it probably isn't significant enough to alter much. If you'd like to compensate for that, do it minimally.

From there (using OEM values in your tune for the trans and H1xx cells), use the speedo calculator with the measured tire height and gear ratio to make your changes. Save File As... to keep a base file and then adjust your trans settings from there.