When you install OS X with myHack, NEVER use Kext Wizard or Disk Utility to rebuild cache. To use the OS X Kernel Cache, that makes the system boot faster, you need to have all kexts in S/L/E. But Hackintoshers don't like that, it is way nicer to have everything inside Extra.
Conti, the creator of myHack, designed some things to use Kernel Cache with the kexts inside your Extra folder. It will create a myHack.kext with all kexts inside it, so it will load inside /Extra. I don't know exactly what myfix does, but I can say it's better then Kext Wizard.