Running the MM3 Lite Version from DRD and love it. Considering springing for the "Switch" upgrade. Fully deleted including heater grid. Came with tunes pre-installed for my application and worked right out of the box. Easy to install. Easy to program. Easy to operate. What's more, you get the legendary customer service from DRD as well. Feels like a new truck, no regrets whatsoever.
I did want to mention something quickly for the guys running Amp Research steps that plug into the OBD-II port and are considering an MM3 tuner (or vice versa). While Ray at DRD advises against it, I went ahead and bought an Amp Research OBD-II splitter so I could leave both my steps and tuner plugged in. However, on Ray's advice, I did the initial programming of the ECM with the tuner plugged directly into the OBD port. Afterwards I installed the splitter. I have been running this setup now for about a week and have changed power settings on the fly numerous times and haven't had any issues whatsoever. I did a lot of research on this subject before I bought my tuner and there isn't a lot of info out there about it. Be aware that some guys have bought the less expensive splitters at Amazon, etc. and a few had their steps cease to function. A few others managed to cut the OBD plug and successfully hardwire (not an easy task). That wasn't an option for me. Just some food for thought...hope it helps someone.