New Kitfox 4 912 muffler

[Av8r3400]

Just a thought
Having struggled with various 912 muffler issues, mostly broken stinger welds. We got serious and pulled some apart.
The kitfox had remnants of an internal support. We rebuild them now with a full length perforated pipe that is supported at the far end by a slip joint to allow for different expansion rates. I assume this is the current way the mufflers are built? 500+ hrs on mine no problems

I have had two of the "internal slip joint" mufflers fail. The first on my 912UL powered 4-1050, the second on the Mangy Fox. I have the second on my bench waiting to be disassembled for autopsy and possible rebuild.

I still believe the failure point in the design is the sleeve joints from the muffler to the header pipes not allowing for any movement. Every other system I have seen have utilized ball and socket type joints.