Sumo is very effective!
My streamline without the sumo sounds like a .22 powder burner....with the Sumo...it's a Pffft! It's incredibly quiet! It is the most effective on this gun for some reason. I have several shorter barreled guns and have several sumo's. Yet on the streamline, the difference is the most significant. I assume it is due to no shroud and the longer barrel. When I lived in town, my neighbors had no idea I was even shooting the streamline!