IIRC the E86 manual is 3.46 with the E85 3.0Si manual equivalent being 3.23. They both have exactly the same gearbox so its this different ratio diff that makes the E86 feel livelier. The prefacelift 3.0i manual also uses the same gearbox as the 3.0Si cars but with a 3.07 diff. Again this is part of the reason the 3.0Si cars feel a bit livelier than the pre 3.0i cars