Rerouted route and output headers

[eluser]Unknown[/eluser]
I'm now getting around it by setting up a controller called maps and putting redirect logic in the constructor

Code:

class Maps extends CI_Controller
{
    function __construct()
    {
        parent::__construct();
        $this->load->helper('url');
        $uri = uri_string();
        $map = explode('/', $uri);
        $map = $map[1];
        redirect(base_url('downloads/maps/'.$map));
    }
}

If anyone knows how I can do it the way I want in the post above then please let me know

Thanks