Its probably already been mentioned(or you already know this) but they have speed related power steering. It should be nice and light at low speed and firm up to give good feedback and handling at speed.
It could well be down to wheel choice. When i bought my car it had nasty heavy replica cup 3's on and the steering was nasty as hell and simply felt wrong. Light with no feeling at low speed and even lighter with even less feel at higher speeds
I have just fitted some forged 16" teledials, the correct wheels that my car left the factory with, and the drive has been totally transformed!! I simply cant believe the amount of feedback im now getting through the steering wheel. Its nice and light around town and it firms up beautifully at speed and gives me so much more feedback and confidence to chuck it into the bends etc.
The heavier wheels mess up the geometry of these cars and im sure, must play havoc with the speed sensitive power steering.
These cars are very sensitive to even slightly uneven tyre pressures, so heavy wheels will totally mess up the geometry of the set up these cars leave the factory with.