I dont think there is any screw you can turn to tighten the response, but rather work the whole steering system. One thing to start on is replacing the bushings with polyurethane or stock rubber depending on what you want. Suspension can change the oversteer/understeer of the car as well as giving you a different feel for steering. Oversteer is turning the wheel and having the back end come around while understeer is turning the wheel and the car doesnt follow. For example, when you go around a turn and slam on the brakes all of the weight shifts forward onto the front wheels and creates an oversteer, while stepping on the gas through a turn will shift weight backwards and create understeer. Nothing will wear abnormally if you drive it properly and never go over the speed limit, and always treat your car with kid-gloves. Otherwise, the tires would feel the brunt of the work probably.
http://www.champcarworldseries.com/Tech/Understeer.asp