Looks like a durable muffler. Haven't tried it yet. I compared two mufflers: a Dynomax Super Turbo 17662 Dynomax 17662 Super Turbo muffler and a similarly sized throttle muffler. Muffler was cheaper. When I received it I looked at the tubes and saw that they had shallow round indentations, maybe 1/4 inch deep, pressed into the sheet metal. Is that your "river guide"? Nothing beats the muffler cross section diagram, which shows a semi-circular mount at the end of the flow tube. Use a throttle muffler, both have the same metal body and save some money.