Funny, I drove the exact same car and I had to stiffen the real stabilizer to make it just a tad more tail happy and less "I'm a brick" understeery .Not a big fan of these S2000 cars frankly - I found they are quite instable and don't suit my style so well.
Have you noticed how close we were throughout the stage? Something like +1.2, +0.06, +0.48 for me on the splits .SS8 - run here a couple of times before and did fairly well, winding up 4th.