I am glad that you like the X11D, its a superb amplifier, but just don't run it at 1 ohm.
Since every amplifier becomes really power hungry at 1ohm and our cars electricals are not meant to meet those high current demands therefore its not advisable to run at 1 ohm (unless you have some really strong electricals upgrades such as good wirings, alt, capacitor, etc).
More over poor electricals is the main cause of amplifier failure, when the voltage drops below 10 volts there is a fair change that you might cook your amplifier.