You need to know what's in the shocks. High grip you might want to try something (from what I remember 40wt #2 piston front and 35wt #1 piston rear. I agree a roll bar on high grip can help. I used to run the soft quite often indoors and the medium one occasionally on very high grip.
Does it actually oversteer and or griproll? Personally on very high grip indoors I'd usually trim the inner and outer spikes off the front tyres and just outer row off rears to fell make it less edgy.
Obviously the best option though would be to convert it to an X6
