Can I install BetterLinux on top of CloudLinux?
No, and here’s why: 1) CL is based on OpenVZ, which we don't support. 2) BL & CL both try to control some of the same things, introducing competing functions and commands. 3) CL & BL use different kernels, so anytime you upgraded one, it would get rid of the other.
Those seeking the best possible server performance are better off uninstalling CloudLinux, installing BetterLinux, and then taking the time to use BetterLinux’s more detailed customization options to make things just right.