a stronger steering servo will turn the wheels better under loads during corners, faster throttle/brake servo will make better throttle response and faster braking, mostly for corners when you want to get the car to break free to slide around, you can tap the brakes then punch it to kind of drift a corner.
there is nothing wrong with the 985 servos, i use them on my cars, mostly steering. i go for a faster throttle though, i have a futaba s3010, which is a bit faster but not as much torque.
my truggy pushed too, if you run the front sway bar looser, move the links as far out on the end of the bar it will loosen it. i removed the front one from mine and liked that even better. it over steers a bit though. try it, if you don't like it, change back!