well raising the rear of the car is a way of changing the castor angle, if you don't have any adjustment of the front end, it's a common thing to do in bikes but you'll know that and a way to increase castor in road cars.
for the mini try as other have said in the posts,
but find a track you know and do a few tests,
maybe even go a bit extreme and radical,
move the brakes all the way to the front, see what it feels like, then reduced the brake pressure a bit, run max fuel and see what that does
then move the brakes all the way to the rear and try that
then try max coast,
0 % coast = max lock up, more throttle control when you lift
100 % coast = free wheeling, less throttle control when you lift
there is a very good GTR2 setup guide kicking about on the net, somewhere.