Also take some time to get the steerring trim on the TX right, and it should be done everytime you turn it on. Well it's one of the flaws of the mini-z
try change the tires to 20, world of difference. if you still experience oversteer then change the fronts to 30 but only the fronts. Tires is by far the most important hop-up for your car so try out some different combinations to see what best for your driving style and surface