Does anyone know the relative stiffness of the two Mugen rear sway bars compared to the stock rear bar?

 

Hey Mike... I could do the calculations, but after driving back from California I'm just too lazy! But I wouldn't recommend the smaller rear bar by itself. The stock rear bar is 28mm with a 4.5mm thickness if I remember right.

Now, conventional logic says that a larger rear bar will decrease rear grip... but on the S2000 it seems the stiffer you go in the rear, the better. We are running the factory rear bar on the project SS2000 with the Mugen coilovers. I had the best balance at Laguna with the rear shocks turned all the way up. Fronts were also at full stiff, and we had a Gendron adjustable bar at about 1/2 stiff. Because of the bump-steer, it seems that the more you lock down the rear of the car by stiffening it, the better it grips... by allowing the tire to do it's job without toe change.

I'd stick with the stock bar and work with a larger front bar... however if you want to play with spring rates, higher rear spring rates with the smaller rear swaybar would probably work really well... By going to higher rear rates and the smaller bar, the car will put the power down better... the stock bar is enough to cause inside rear wheel-spin in the autocross environment, but on the track I don't think it's a factor. Give Scott a call up at King and talk to him about it.