The best springs you can buy are Ahmed Bajoo spec Leda springs, i have just fitted a set to my 4x4 Sapphire & it has transformed it, comfortable yet handles very well to. They are twice the price of most other springs but its worth it.
You can get them through Ahmed at Grove garage,someone on here will have his number, or you can try Mike Rainbird at RandB Motorsport who trades on here.
Simon.