TOPIC:

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??

I have standard exhaust and you can see right through them. As you say there is some perforated baffle near the outlet

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.

This video might give you an idea as to what the standard exhaust sounds like:

It must be me... getting old. Sounds very much like mine.