What kind of screwed up tranny ratios do you have?
4th should be close to 1:1 on any 6 speed manual, on a stock S2000 it is 1.1:1. 5th and 6th are overdrives, but 5th is still close to a 1:1.
Stock S2000 Gear Ratios:
1st: 3.133
2nd: 2.045
3rd: 1.481
4th: 1.161
5th: 0.943
6th: 0.763
Reverse: 2.800
Final Drive: 4.100
Secondary Gear Reduction: 1.208
PPG's ratios usually are:
Ratios: 3.16 / 2.09 / 1.53 / 1.22 / 1.04 / 0.88
As you can see, only 6th would be overdrive.
Are you using their drop gears? They don't list the ratios for them, but they should be similar. Why would they make 3 OD gears, except for top end runs? You might want to double-check this. If they really put 4th as an OD, then they ripped you off with a poor tranny setup in regards to performance.