mmmkk,. there's a couple things to take into consideration when tuning for stiffness.
1) Do you plan on riding the rumble strips or driving a 'hilly' course?
if yes = try a softer set-up in the springs. I like to stagger my springs when I know it's gonna be a bumpy ride. With springs low on the front (4-9), the car will hadle the big bumps a little better (especially 'riding' the rumbles). The rears should most always be tight (the only time the back shouldn't be tight is if your drifting waaaaaay to much. I usually use something along the lines of 14-20. The higher the number, the better your acceleration performance will be through the grears (though don't confuse it as a grip helper of the line, it's not).
if no = you usually want an even setting. Very rarely, but occasionally, I'll drive them at 4/4 or 20/20,.... you'll have to find out when and where you like those extremes.
Also remember, springs effect ride height. The higher(tighter) your springs are, the lower you can go with the height. if I have a 4/20 setup on springs, I'll usually run the front mark at about 3/8 and the rear at about 1/4.
Hope that helps 👍