Ok but I did read about someone destroying a cheap 2pc set on 928 springs and ended up using 2 2pc sets. So a 3pc set seems a better idea than the 2pc ones perhaps.
I've now seen new springs for £34.75 each on ebay which is tempting but I know if I touch the suspension I'll probably end up replacing more stuff. I've just spent about £800 in parts. Glad I'm not keeping a running tally
Here's the ebay springs. Anyone heard of SUPLEX?
http://www.ebay.co.uk/itm/1-x-Front-Coil-Spring-PORSCHE-928-5-0-S4-01-08-1986-01-07-1991-/231386775571?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Car+Make%3APorsche%7CModel%3A928&hash=item35dfba0013