Biggest change you can make is tyres. Harder compound on the front if allowed. Also, glue the sidewalls to take away some of the bite. I would also run the stiffer settings on the front compared to the rear, and make sure you have a little more droop on the rear than on the front. I also run 3 deg rear toe in now as it makes the car more planted. Diff setting makes a big difference too, a stiffer diff (within limits) is going to make the car less sensitive on turn-in.

The other thing is driving. You need to be smooth on the steering and throttle inputs. A mini won't appreciate the hard inputs that a 4wd touring car can deal with.

I've discussed servos many times. I always use Futaba because they perform well, last a long time and are reliable. My oldest 9550 is over 8 years old now and still going strong. Makes you question how much you are really saving by buying a Savox or PowerHD that is going to give you hassle.