This previous thread might shed some light on this and shows the type of springs fitted. No tender spring.
http://986forum.com/forums/general-discussions/63679-kw-coilovers-bottoming-out-badly.html
Definitely progressive springs - not standard "straight" coilover springs. Not sure you'll find anything out there to substitute.
Try contacting Casten at KW and see if they can overnight you the right spring. I worked with him on some issues I had with my V3's on my TT and actually visited the plant here in CA. Not sure if he's still there though......
carsten.wagner@kwautomotive.com