Hi thanks for your help!

Never thought of trying this and it has certainly put some issues to rest. I tried this and measured the diameter when turning left in a circle on full lock left and right with the throttle trim set to the lowest point where the vehicle will still actually move. The diameter for both is just over 5ft, give or take an inch for each one. This level of error is acceptable enough for me to be happy with.

With the collars now level the car still spins out more when turning left than right, although not quite to the same extent as before - I reckon its probably manageable now. Trouble is the car is quite happy to spin out when I put the power down now in either direction. Not sure if I'm expecting too much, my driveway is smooth asphalt and Im running a 13.5T BL. I dont run asphalt very often aso not sure if this is what to expect or not.

I'm happy to take the car to the track tomorrow like this now, however if once the tyres have been prepped and heated I'm still getting power-on oversteer on the proper racing surface of the circuit what should I adjust to fix this please? I only know of softening the rear springs, adding rear toe in and slackening off the diff. Should I lay the shocks down more etc..?

Cheers!