As far as I can see all Morgans are not created equal in the area of front suspension. Some people who have fitted the steering bearings to replace the blades have had shimmy problems because of insufficient castor angle. This has not occurred on all cars but where it has occurred the fitting of a steering damper has resolved the problem. When Morgan started fitting the bearings in production they increased the castor angle and this has resolved the shimmy problem.
When a Suplex kit is fitted the lower spring is not loaded at static ride height so the steering bearing is not compressed between the two springs but carries only the weight of the car. In most this would reduce the load on the bearing so the steering does become lighter by comparison to the standard springs. I believe that the Mulberry set up also uses a very lightly loaded, but stiff, lower spring. I would think, therefore, that if you are not experiencing a shimmy with the Mulberry set up it is unlikely that you would experience a shimmy with the Suplex.
Peter Mulberrys kit uses the standard lower rebound spring so it's not a case of it being a stiff lower spring so much as it's the OE spring. The main spring is" different as it's shorter and of a different rate to the OE Main. Suplex suits some but not all owners, some love it, some are indifferent and some have had it removed as they did not like the handling afterwards. It certainly does change the comfort level and having followed 2 cars with the kit fitted (one was one of the ones I have fitted) you can certainly see the difference Suplex allows the road wheels to move at a different frequency than the bonnets, to explain if you look at an OE equipped car the bonnet line and road wheel tend to move at a similar rate, with the Suplex fitted the front wheels can be seen to be moving independent of the car and it's isolation from road undulations is far more apparent.
