This is called a "Jim Lomas"- RZ Mark Two expansion chamber exhaust system.
SIP has a very detailed description for your information.
Intended only as a tuning exhaust for modified Vespas as SIP details. Right hand exit.
You can also look on the website of LTH using the nomenclature marked on the muffler in Google search:
JL BS AU 193A 1990T2 P200
See SIP listing for-Article No. 25051300 @ $228.70 plus $45 Fed Ex to KY from them.
Mfg by LTH for the Vespa P80-150X/PX80-150E. LTH, lists for 215 euros in Europe. Use on Sprint, Rally & 200cc models.
This is the SS version in satin black paint with polished SS muffler and no db killer. 43mm connection with integral clamp.
All mounting hardware enclosed.
Pictures available but I strongly suggest you look on SIP's website first! Online pictures are exactly as the system exists!
$125 plus actual cost shipping from KY to you.