Originally Posted by Z00M

Fred, details of the changes between the G4 and the G4S are noted in the very first post of this thread.

I ran both the G4 and now the G4S and I can tell you the car is much more balanced in G4S form and the UFO clutch that is standard on the G4S is well worth it as well.

You can also buy an upgrade kit from the G4 to the G4S but this doesn't include the UFO clutch.