For the Special Time Trial you can't make changes on the setup given.
If the X2010 given this weekendis the first one on your garage, the X2010 is a VERY special car, the way it must be driven is completely different of any other car in the game. Where you have understeer in other car, you realise the X2010 steer too much, you have so much grip that you can smash the throttle without wheelspin, that kind of stuff. That's not a setup problem, just the way the car is. You must change the way you drive. I prefer not to do it, so I don't use the car in A Spec mode, because I can't handle it, It isn't fun to drive it for me.