One factor not mentioned yet is tire selection.
Natural rubber: pink, magenta, purple will provide good grip but at the expense of rolling resistance as they gum up. They are needed in low grip or high power mod racing.
Synthetic rubber: black, grey, yellow will not pick up or gum up and have lower rolling resistance. This is important in 17.5 racing.
Large diameter tire also have more rolling resistance.
Car setup should not grab as you turn in and kill the corner speed. In other words work on the setup so that the car doesn't slow down too much as you turn in.