When I recently bought my z13, it seemed somewhat louder than I remembered from years gone by. Looking down the silencers they appear to be straight through construction, just a perforated tube end to end with no baffles as such. Is this how they all are??
Yes, they have resonating chambers that the perforated tube allows the sound waves to expand into, for certain frequencies to be cancelled out. The small boxes just after the collectors act as a pre-silencer too.