Would def get some handling mods! Either WALK (Whiteline Anti Lift Kit) or SuperPro anti lift kit, SuperPro lower engine mount (for the price, v good), H&R springs, an Autotech Rear Anti Roll Bar and as the others have said, brakes. Check out the thread on NSQBBK, for the money they can't be beaten.
For your money, stage 1 map, loads to choose from.
If you have a manual and you add lots of power (torque), a upgraded clutch will be needed.