RE: Ryobi 31cc Stock Muffler
I put one together with the Wacher Engines parts including his small dual pipe exhaust. It worked great, but I did not like the high noise level. I put the stock, much heavier muffler back on and the noise level is much more tolerable. I would say try it like it is and see how well it works. If you need more performance than try gutting it. Just my two cents worth.