RE: Norvel Engine FAQ
Here are some of the muffler changes on the .049s and .061s.
On the earlier AME the muffler just had a hole where it attached to the engine and was prone to rocking back and forth, giving a poor seal.
After that the muffler had a smaller hole in the stinger and the spring clip had the tips bent down, making it much easier to install and remove. The newer mufflers have a shoulder making a much better fit to the engine.
The latest muffler has a slightly different shape.