Can anyone give me some ideas on what would be the best gearing for performance? & which manufactures supply it? Thanks

 

Your question is not specific enough to return a valid answer. "Best" gearing depends on what you plan to do with the car. One F.D. ratio may be good for a given track or application but horrible for another track or application.
J's makes the 4.3, 4.44, 4.77, 5.1 but the 4.44's are almost non-existent and the 4.77's are much cheaper if you get from Kia.
Rick's Accessories (a board sponsor) sells the 4.57.

ps. Moving to S2000 Talk. When you want to know about how to install them, post back in UTH. Thanks.