gear ratios for the R200 differential (NA). They range from around 3.xx to 1 to 5.xx to 1. As I'm sure you know, the NA diff. uses a 4.08 to 1 ratio. But as Guapo pointed out (In his unique sarcastic style) you will be cruising at pretty high RPMs at normal highway speeds by increasing your gear ratio. But to answer your question: yes they are available from Nismo for about $677 (retail) and will allow your car to accelerate more rapidly until you run out of your power band. I don't know where that is in an NA. Hope that helps, Mark