CMD is made by DynoJet, if there's a company calling their's CMD too that'll cause some issues. But just incase you meant DynoJet..
The CMD is a piggyback system, it takes what sensors are actually doing and then modifying the values to send it to the ECU. That way you can operate the engine beyond the limits of the stock ECU or make changes for throttle control or injectors without having to get a tune just because you wanted to make sure you had some headroom.
Piggybacks are NOT for newbs. If you've never tuned before, you should not use a piggyback, they're not the safest method of getting better power. They're actually, basically, a watered down Haltech ECU replacement. Because CMD's don't have cam control and other features that a full ECU replacement would have if you're not careful you can very easily blow your engine apart, loads of people have done it.
I've thought about using a CMD just so I could put bigger injectors in and still leave my ECU stock but due to my lack of tuning expertise, I haven't done it. I have all the software and have played with it on testbeds but that's about as far as I've gone.
If you want to play with the software a bit to decide if it's for you, you can download it Here
, load up the sample GC map and tweak and read away, you might need to watch some vids on what it all means but I think for tuning, the software is pretty straight forward.
It's not a bad product, don't get me wrong, I just don't believe it's for a novice modder or someone who has little to no tuning experience.