I wonder if the difference that he's seeing isn't just the difference in the sidewall stiffness of the two types of tires. The sidewalls of the S03's are considerably more flexible than the OEM S02's are. Just try to gently push your car sideways with the OEM tires on it and you will see that there is no play at all. The extra flexibility of the S03 sidewalls will make the car seem to be less planted and more wishy washy feeling. It will feel like there is a big time lag in the steering response, now. I have seen this difference before with other cars and to me it was a big disappointment after putting new tires on my performance car, only to find out that it drives like a totally different car, now.