There supplied by ABP as you can see on the springs they have there stamp on them also, 30mm all round. They havent settled in yet, that picture was shortly after they were fitted, just about right height i was looking for really, the front just sits on tyre lip. After a few weeks when there bedded in and torsion bars tightened again ill put another one up to compare.
Alot of guys go for coilovers on front with these springs on back, reason being they want it lower on front. Any lower wouldnt be great for handling and like you said front track rod wear.