To hide Navigation bar on using Vimperator you do not need to install any other Addons.
Use the following command to hide Navigation bar in browser, and this preference will be Absent after restarting the browser.
You have to store your preferences in the file .vimperatorrc to get load on Browser start up. At first, you have to create the file and name as .vimperatorrc without any extention in the following paths.
/home/[your user name]/.vimperatorrc
Windows XP C:Documents and Settings[your user name].vimperatorrc Other Versions C:Users[your user name].vimperatorrc
No extra permission is needed. Then, open the file and write :set gui=nonavigation and other needed preference.