NormK they added a heat shield over the exhaust which has a slight effect but certainly not worth the extra (see photo).
This was the more sensible (and a bit cheaper) model to get at the time (in link below).
Most of the main benefits that count, without the drawbacks of the full cover. Better heat dissipation too I'd imagine.
https://collection.maas.museum/object/158742#&gid=1&pid=2

Attachments
IMG_20210301_184711-1000x564.jpg (60.06 KB, 94 downloads)
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!