Generally speaking I think the Yosh exhaust is louder by nature than most other options.
At least based on what I've read on these types of forums.
I know nothing about the insert you mentioned, but I would ask if you have any clue how long it's been since the muffler you have has been repacked?
I assume it's like most other after-market mufflers for the r/x line and that it occasionally needs to be repacked?
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2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs