An 'old' Morgan engineer/race driver called Colin Musgrove designed a couple of good ones. The ones I see at the factory increase rear spring rate too much in my view. Not a lot of space to do much different from the factory or MulFab, so they stop windup and tramp but stiffen the rear rate. Fit such to go racing with a big motor or not for fast road work.
I like the option of tele dampers mounted leaning fore/aft as the aftermarket fitments are as these dampers then work in axle windup and damp it down, the current damper arrangement of them leaning in at the top are far less good at damping windup - there's progress again - not. Mmmmmm! PJB