Following instructions are provided without any warranty, and may even get you in trouble legally. The instructions are provided for testing, learning, preventing e-waste, and should be use with care. We (including contributers + commentators) are not responsible for any damage to your device(s) or any legal issues.
Instructions have been moved to https://github.com/francoism90/asus-router. :)
Interesting on my GT-AC2900 160mhz becomes unavailable if these entries are set to anything but undefined (default setting):
I have to clear nvram to enable 160mhz again, nvram unset doesn't work. Not sure if all three entries cause it to break or just one of them.