I just had a Viper DS4 installed in my 2012 QX56. It works off the 3x lock, I also bought 2 remotes as well. (range is not that great on my factory fobs). It has bluetooth for the smartphone. I can lock, unlock, start car from about 150 ft away. But the viper remote has great range. The remote starter works well. I ended up paying about $350 for the whole package with a 2 year warranty from Mickey Shorr. It also included a T Harness with simplifies installation (less wires to cut) . THNIN3 is the part number for T Harness about $29. The fact that it has a bluetooth app for the smartphone is cool at first...but you will find yourself not using it at all. However, if you buy "smart start" it will allow you to start, lock, unlock from anywhere, have to buy another component and pay about $70 a year. By the way. I called Viper to ask about voice control. I was hoping I could say "Siri start my car" or "Alexa start my car" . But it's not available...and might never be. If you have any questions...let me know
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