I have never had any luck with YS mufflers.
My FZ 1.20 muffler broke of in flight...at the bend in the header pipe. Clean break!
I was just so angry with the quality that I carried on flying through out he day making one hell of a lot of noise.
Any complaints should be forwarded to YS etc.
Yours is just wonderfull, never seen anything like it.
Send it back and make some noise yourself!