Far be it for me to criticize someone's setup, but 600 lb. in front springs on an ITS S30 is at least 200 lb. in. higher then I've heard anyone run, and that includes the Chet Whittle/Keith Thomas ARRC winning car. I do know of a few guys down in Australia running 600/450 on their S30s but they have a lot of chassis reinforcement done and are definitely beyond IT levels of prep.

Maybe it works and more power to the folks that make it work. Its always better to try something different with the chance that you'll make your car faster then to copy and know your car will be just as fast.