In my testing outdoors the car is loose at the rear because it is rolling too much to the extent it's rolling off the rear tyre. It needs to be much stiffer in roll. Hence the blank pistons and 2-3k oil in the roll dampers. I'm up to using blues and grey springs in the roll dampers and the car is much better. I don't have the loose rear-end anymore in high speed corners. It just seems the harder I go the better the car gets. Bear in mind I'm running all the latest parts. I'm actually 1mm less shims under the rear upper arm mounts too. The car is getting better every run.