The pictures show a Rossi pipe. hard to tell nut it looks like the onr that came with the Rossi .81 NOT the .91. Neither will work with a Byron Fan unit. The Rossi .91 runs too hot on a byron fan and they will melt. I don't know of any one that still makes a pipe for the Rossi .91 and a Byron. The only suggestion I have is replace the Rossi with an OS .91 DF engine. with a Weston mini pipe or TGA (Byron) pipe (If you can find one)