s30z

The Z does squat. Just because you do not feel does not mean it doesn't.
It's funny how you brought up robispecs car because Sway bars have no effect on rear squat. With all the aero he has in the front maybe he was trying to induce a little more understeer. But look at his spring rates. He runs 8kg in the front and 10kg in the rear, without a rear sway bar.

The main vehicle you should be looking at though is Paul Dentice. AEperformance 370z. The car is stock no aero with jic coilovers and a big brake kit. Consistently dominating the timeattack scene and his front to rear spring rate bias is pretty big, if Im not mistaken it was like 14 in the rear and 10 in the front. This car beat out Robi's 370z, and the AEPeroformance 370Z is pretty much bone stock.

You also have to understand that even with these big spring rates it does not mean its really stiff. The rear of our cars has a pretty extreme motion ratio because the rear spring is seperated from the shock. This is one of the reasons why the rear spring is raked up so high.