Hmmmm..... to some degree at least it must be the way you're entering corners, maybe too hot? Last time I had my Crossfire on track (also stock tires, alignment, etc at the time) I managed to hunt down a Spec Miata racer running R-compound tires and finally over take him. Yes, he schooled me pretty well for a couple of laps, but once I figured out how to stay with him in the tightest sections of the track I just powered by him on the main straight and that was that.

I used to have a tendency to enter corners too quickly and I think that had a lot to do with the car not wanting to turn in as well.