its not so much the '-20mm' drop or whatever the ahmed springs claim to be, dont be fooled into thinking you need a specific drop.
the escos needs to be at a certain height front and rear to enable them to still squat to a slight level, to have the correct roll points to handle correctly, and the ahmed springs achieve this perfectly, matched with a set of Koni's and you will find they will give a much better road feel, overal drive and handling ability than the entry budget level of Gaz coilovers at £500.
but as said, if you do go for Gaz coilovers, order them thru Chris oe Mike as they spec the springs slightly different, Gaz spec them ridiculously hard.
prices here
http://www.randbmotorsport.co.uk/shop/Parts.asp?ID=5
now get yourself over to
www.escortrscosworth.com