There were 3 colored keys available when the first Commander rolled off the line...1 black and 1 gray were supplied to buyers......black was unlimited power and gray was restrictive to about 45 mph with noticeable torque loss thru the rpm band. Many peeps have gotten their machines with the black key programmed to gray key restrictions by the dealer, and your case sounds like this may be the problem with yours.
Turn your key on, but don't start the machine and read your scrolling display. It will say what the key is programmed for....black usually is performance. I would check all keys this way. Let us know what you find out.
Dealers can program the black, gray and orange key to any of the programs you tell them you want. We have all our gray keys programmed to black key performance level. I've been told dealers can program up to 8 machines the same....meaning if you had a fleet of 8 Commanders and Mavericks, 1 key could work in all 8 machines...a fleet key so to speak.
Before doing anything else, key your 4 keys sorted out....you may have 4 keys programmed to limiting you at that 45 mph level.