That means that the times I was getting for the 0-100km/h (6.15) are similar to yours when coverted to m/h ie. 6.15 - 0.4 = 6.75. I could do consistantly times around 6.20 but when I got it a bit wrong, I dropped the time down to around 6.4. Though, when I let the revs drop to about 5k or less (when the wheels stops spinning) then I easily stretched the time to high 6s (around 6.8). Also, when we (me and 2kturkey) dropped the clutch from low revs (2k - 3k) then we stretched the times to mid to high 7s. As you can see, it's eazy to have a slow launch with the S2000.

Wondering how fast the BoxsterS and M roadster are? I will quoute local number (Australian and for 0-100km/h):
-BoxtsterS - Best time that I have seen is 5.70 but more often than not the BoxsterS time is around flat 6. I have seen one as slow as 6.6 though.
-M Roadster - Best time I have seen is 5.60 but usually the time is more like 5.9. Slowest one I have seen is 6.3
-S2000 - Comparing that to local numbers for the S2000 it makes both these cars faster for the 0-100km/h run. Best local time for the S2000 that I have seen is 6.42 but usually I see 6.6 times. Slowest one I have seen is 8.3 ... don't ask me how they got that as I have no idea how to go stat slow, though I do know that they had a badly slipping clutch ... still must have been a really slow day (ie. bad air) for the S2000. Though, both me and 2kturkey could repeatedly do 6.2 times with the Gtech and then with a bit of effort 2kturkey managed 5.85.

Going by this, the BoxtserS and M roadster are unlimatelly a little bit faster ... though, on a good day the S2000 will be close behind when all cars have a perfect launch. On the other hand if you're having a good day and they're not and the air is good then it's more then possible to beat these cars when they're not performing at their optimum or don't get the launch right (which is not hard).

ps. I see that you're talking the 0-60m/h times, so now your numbers are clear.