You need to realise you are now driving a powerful, heavy, rear end happy car. No offence, but you need to drive properly. On and off the throttle nice and gently, same with the brakes, and loading up the tyres. There no understeer safety net with RWD, if you boot the throttle the rear end will come around on you in the wet.
I suggest you all read/watch "A twist of the wrist". True its all about riding a motorbike, but it will make you a far better driver
Personally, I'm planning on doing a CarLimits training day with Andy Walsh next year