Looking at the brand markings on the top of the callipers it looks like the manufacturer is 920Engineering.
See:
https://shiftec.com/about/Looks to be a bit of a messy history/status of brand names and ownership, but on the face of it 920E appear to have a good pedigree in motorsport.
Ignoring specs for a second, what I would say is the hire Plus Four I drive in 2021 had much worse brake performance and feel than both my Plus Four and that of the one I drove on the Driving Academy day (which was absolutely fine after 2 x 1 hour sessions on “track” at Bicester Heritage). The owners manual makes it clear that they are single piston callipers on the Four, front and rear, albeit with different size discs. The Six has four pot front callipers. Whilst I have no issues today it would be something I might look to upgrade in the future; if only to maintain braking performance over repeated descents in the Alps. If anyone is interested it looks like the dampers are made by SPAX, at least from what I could see on my front dampers with the wheel still on.
