Craig,

Try a new set of M grips on the rear and a worn pair on the front and drop your ride height by decreasing the spacers on the standard shocks. The new M grips son the rear should assist with stopping the back end getting loose.

Another option would be to try S grips on the car, however I am not that familiar with them, as we can run open tyres and most of track surfaces are asphalt.

Regards,

Calvin.