Neuspeed's rear sway is 22mm, just like the ST. I'm not sure on the Eibach, but they only sell the sways as a front and rear kit, and it's overpriced. The only reason I didn't go with the Neuspeed is it only works on cars with a factory sway bar. The ST is the only one I know of that allows adding a rear sway with no drilling or welding. I HIGHLY recommend the ST rear sway bar to everyone.

It's just $140 at Summit. here's the link:

http://store.summitracing.com/partde...5&autoview=sku