I have to do a 576 MM on a customers saw and will take some pistures of the process. Some of the Husqvarna saws don't leave lots of room to either side of the muffler for a round tube. So a piece of oval tubing from a bicycle fork will fit where round won't go. Also the lower rear fork makes for some nice oval tubing also.
I look for the old styles with lots of gentle curves like the first image.
The second image will give you more details.