Finally there is an official way (no myspace code required) to have top 16 friends (or top 12 or top 4). To activate this feature do the following:
1. Add X-MEN : The Movie as a friend.
2. Click "Home" to return to your myspace home page.
3. Click "Change my "Top Friends"" link under your friend list.
4. Now you have the option to change number of friends in your top (see the screenshot below):