Felt like making some noise. Tried my AX with the 10-6 on my Twist with no muffler. 15,750. With the muffler was 15,300. Maybe the baffle was not in. Not sure, seemed kind of loud. It seems like the FX, AX, SF and most of the similar ones all run about the same. The AX is maybe a bit under the FX, but the newer Powerbox muffler makes that up. Same sh-- different pile. My Royal one was up there too. I have sold it since then.