silly question, but when you say the back kicks out are you coming off the accelerator? at the time?
Scoobs suffer from liftoff Oversteer.
As has already been mentioned tyre pressure, the only other thing I can think of is Crap tyres TBH, if they are a budget make I think that's the most likely cause.
If you can go for a better make of Tyre like Falken, Goddyear, Vredstien, Toyo, Yokoham etc.