Here is a picture of a muffler I modded for a friend. He wanted more power from his 455 but before I finished it he had bought a new Stihl 362 and was happy with that. If you want to copy this modification, it is not hard to do. If you want to buy this and have your old one for a spare then $50 and it is yours. As you can see the screen is still in place but it has a much larger opening. Mike