http://www.intense-racing.com/pics/p...4834_small.jpg
Make it look like this and be done with it. Unless you literally open it to a full square and the rotors can't push against anything...you can't really screw it up. Not to mention you will notice nothing for performance gains and just a little more noise.
However two additional things; no need to really open the silencer ports anymore.
At the top right and left; the square edges...remove those and open the triangle outlet all the way.
Only things I would change.
I miss my old ported GenIII though...whistled like crazy.
https://www.youtube.com/watch?v=8S7v4HZF11E