So I made a start by reading everything Jay Mitchell had posted about suspension developments on his S2, several websites from people in the suspension business and even a few of those old fashioned things called "books".
It was hard going.
At this point I'll cut the story short to reduce boredom and say I ended up with 250lbs/ins front springs, 160lbs/ins rear springs.
But if you really would like to know what was cluttering up my mind during this process and how I got there, try the link here
There is geekiness and several questionable assumptions - you have been warned !
Adjustable Protech Dampers and Springs
Sleeves to mitigate the coils rubbing on the body
So, the new springs and dampers arrived and were assembled. On the rears I fitted sleeves to prevent the springs rubbing on the damper body and also the OEM dirt shields for the top of the dampers.
A few gentle rides around the block to settle it in and then a full geometry check to ensure we had something like the correct alignments.
That done I begin experimenting with damper rates, eventually settling on them mid position in their range.