ok sexcbum calm down no offence was intended it's just that a lot of people do tend to join, ask one or two questions then bugger off never to be seen again. There is a LOT of good info on this site but searching for it can be tricky.
If you happened to be at the track on the weekend there was an extremely quick and tidy coupe there running a nice 4 link rear end. It might pay to poke your nose under the odd car like that before you start. If you're not hell bent on the four link you could always try the JTS springs, there's always more than one way of skinning a cat.