I have an SCT Livewire tuner connected, showing the vehicle speed, along with a couple other sensors. When my speedometer is showing 52, the Livewire is showing 47, GPS and police roadside "Your Speed" signs both show 58. I've adjust the Revs per mile, in the Livewire, based on my tire size, but it had no affect on the speedometer. According to SCT, because I have a custom tune, they cannot provide support, to change the speedometer. If I remove the custom tune, because I have an EGR delete, the truck runs for crap, and can barely go over 35 mph. So, resetting to factory isn't an option. I bought a USB ODB2 scanner, and downloaded FORScan, but all the forum posts I found, reference 2011 and newer. And when FORScan runs, it doesn't show the BCM module, where those posts suggest to make changes. The faster I drive, the further the speedometer is off, so it's getting really frustrating, trying to figure out how fast I'm really going, so I don't get a ticket. The only way I can be relatively sure I'm safe, is to keep my GPS up, on my phone. Any suggestions, on how I can resolve this, other than going to the dealer, would be GREATLY appreciated.