Harris also made 3:1 exhausts for the standard triple.
I had one on my '79 Jota.
Piece of crap performance-wise.
Ended up with 165 mains and a sawn off end cap from a Jota silencer tacked on.
It did not look anything like the one in your picture though Lothar.
Not sure if their 3: for the Harris frame was different or not, but again I don't recall the exhaust on my mate's Harris Laverda looking like that either.
Looks way too modern to my eye.
Then again the collector is 3 in a row flat, and mine was 3 in a triangle at the collector.