Hooks in Codeigniter

$config['enable_hooks'] = TRUE;                  in application/config/config.php

application/config/hooks.php


$hook['display_override'] = array(
        'class'    => 'MySiteName',
        'function' => 'Mysitetitle',
        'filename' => 'Mysite.php',
        'filepath' => 'hooks'
);


application/hooks/Mysite.php

<?php
class MySiteName {

    Public function Mysitetitle()
    {
      $this->CI =& get_instance();
      $mysitename = $this->CI->output->get_output();
      $mysitename = str_replace("CodeIgniter", "My Epploo123", $mysitename);
      echo $mysitename;
      return;
 }
}