No personal experience, but judging by the OD vs. inlet diameter the internal volume is pretty small. It's a straight-through design (?) so it won't affect power much (if at all) but it would be quieter with more volume.
BTW: the usual "tell" visual for straight-through is that the inlet and outlet are on the same centerline (if not, almost always reverse-flow where both pipes are parallel inside an open box with their openings on opposite ends).
However: some apparently straight mufflers have a completely closed inlet tube at the far end, holes drilled or punched emptying into the shell, and the outlet only connected to the shell interior - not the inlet. Backpressure may be very high, depending on what the perforations look like.
