The original installation media for Mac OS X Snow Leopard was a 10.6 DVD. The DVD was only updated once to version 10.6.3. In order to provide more frequent updates to users, Apple is now slipstreaming the latest version of OS X directly into the download. Upon fresh installation, no updating is necessary!
  If you downloaded Mavericks from the App Store prior to December 16, 2013, you most likely have 10.9. To re-download Mavericks and update your Installation App to 10.9.1, simply log into the Mac App Store and click Download. When the download finishes, the app will automatically open. The updated 10.9.1 Install OS X Mavericks App can be found in the Applications folder. You can then re-create your UniBeast installation USB.