Buggy

My 2016 lm 400 seems to be louder than it should be.. I think you must determine if noise is exhaust related or engine internals,[valves etc.], or the clutch drive setup.. The drive clutch uses weights and centrifugal force to engage and can rattle when worn or damaged.

My 2016 LM 400 with the Honda 390cc engine uses the original muffler that Honda puts on the engine. In other words you can use the Honda website to look up the parts illustration and match it to yours unless you have an alteration of the original..Its worth a try.

Keep in mind that the factory matches the drive clutch and belt to the engine horsepower. Too much horsepower will smoke the belt and maybe the clutch.. your factory setup should be ok with a modest upgrade. I think your drive setup can handle up to a 400cca and would not go more than 420cc unless you plant to upgrade clutches and belt .

The Harbor Freight Predator 420cc should work but verify your shaft size and rotation is the same. The Honda 390cc is a great engine but will cost a lot more.