Yes, Regina, was first series 350 but modded for 400 cc and one ex pipe cut and head welded up for mimicking a "Sports" Regina with single ex pipe. This is not my bike but Toni´s, who had troubles from -- warped clutch plates ! So then we changed plates for slotted types , plus he got my 28mm Bing plus bellmouth - goes quite well he reported.
The "stiffening" tubes I´d call homeopathic effect, small plus the bends - hard to notice any benefit on the road . But then various communities got their various "cool" goodies everybody needs for respect. A bit like 2 " ex pipes on Vincents I suspect, nobody elsewhere would want that size on their bikes, not worth the hassle.
Vic
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