Everyone is entitled to their own opinion however it is important that this opinion is backed by some understanding of the principles involved.
The SSL kit has a number of things going for it.
Firstly the ride height is adjustable. If you have a Plus 4 with 195/60 R15 tyres fitted you would be well aware of the ride height problems. I my case I have set the ride height by using shims from the SSL race kit instead of the standard spacers provided and I have fitted 195/65 R15 tyres. Along with this goes the fact that as the springs age I can easily adjust the upper spring to bring it back to the correct ride height.
Secondly the spring kit also includes a rising rate spring which increases the spring rate on major bump compression. Not essential but certainly nice to have and helps with touring comfort and less roll on cornering plus increased stability if a bump is encountered on the compressed (outer wheel) suspension in a corner.
Now let us consider the function of the rebound spring. Firstly, for reasons we'll explained by Peter Ballard, it is important that the rebound spring is not compressed at static ride height. If it is compressed the spring rate of the upper spring is increased and as the upper spring compresses and the rebound spring is released the spring rate drops dramatically. This gives a falling rate suspension system which leads to the dreaded Malvern dance or front end nodding.
If the rebound spring is barely touching the bottom of the sliding stub axle this problem is avoided. The cheap solution is to cut the spring to the desired height but this is not ideal for the reasons previously mentioned by another contributor. A better solution is to get new correct length rebound springs. Having said that the upper springs may need to be replaced too. Either way simple springs of the correct length and rates are a reasonable solution that will not cost the earth.
Removing the rebound springs altogether is not, in my opinion, a good option. Consider this: as the inner wheel in a turn gets light the main spring pushes the wheel down and this in turn contributes to body roll of the car. In the Morgan sliding axle system the rebound spring limits this downward push of the main spring and helps to reduce body roll.
From all this it is easy to understand that correctly fitted front springs improve the cornering performance of the car and I believe that the last of the trad suspension cars where factory fitted with much improved springs.
Personally I took the path of fitting the SSL system as it provided everything needed in one package. Certainly it is not cheap but it is a very valid system. I later also fitted the 5 link rear system which has also been tuned to my personal requirements.
My recommendation is that if you want an economical solution fit new springs of the correct length and rates (important that the rebound spring is not under compression at static ride height) but if you want the best in trad suspension and the expense is not a worry fit the SSL system and be happy with the cars handling performance and improved lighter steering (if the old system was under compression).

I have no interest in SSL: just a happy customer.

PS: even with all this you are never going to compete with a modern sports car with fully independent modern suspension but you will have a notable improvement over the standard trad setup.

Peter

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