I was in the shop (monkeybuttparts.com) when the FMF arrived for F_G's bike.
It looked like a 4T can, only smaller. Maybe mid way between.
A 6 dB drop in sound pressure is significant. A 3dB drop is half. Another 3dB is half again (is that how that works?
).
The only think I'll hear when F_G rolls up is chain noise.