do the calipers bite and then release smoothly, you can test by jacking it up ans have someon press the brake whilst you spin the wheel by hand. only suggesting it cos one of my calipers ( hi-spec )had seized slightly so i replaced the seals. also have you got adjustable coil-overs cos i also had the problem that the rears were too firm and not set right so everytime i braked hard it pulled violently to the left, i softened them to as low as they will go and now it is much better and smoother to drive too.