Which engine are you using? When I started using the 56 a few years ago they still came with the older machined mufflers with the curved header pipe. My 72 came with the new cast muffler that weighs too much and I didn't like the appearance. I ordered a replacement muffler from Horizon that was originally for the Saito 80 which used a curved header and machined muffler. If you are using the 56 try to order an old muffler from Horizon.