[Rwillia4]

Well some shocks will give you a better feel with some springs and generically work better for performance. But the spring and shocks do not need to be changed together. And there is plenty of different opinions of which springs work best with which springs, this is a personal preference that can only be answered by your driving style.

I like a firm/stiff car that doesn't “flop” around a turn and has a much more aggressive breaking point (when the oversteer or understeer begins) and more difficult to control. Others like to have a softer car where the breaking point is much more gradual and easier to control once you begin to pass that point.
Race springs are going to make the car tighter, roll less.

The combination of race springs and stiff shocks will make the car more precise and have a quicker response to any driver input. The negative side is the cars ride is stiffer.
There is another component that can vary the handling dramatically: sway bars or roll bars. These need to be changed out in pairs (front and back) the bigger the bar the stiffer the suspension. What they do is mechanically connect the left side with the right side. So that if the left wheel goes up the right wheel. The distance the right wheel will come up is dependent on the size (diameter) of the bar. The bigger the bar the more the left and right will come up the same distance and the tighter the car. The flatter the road the bigger roll bar you can use. You will increase your capabilities, but there are some downsides in ultimate controllability.

Example: If your car is stiffer the result would be similar to running to a cliff edge as fast as you could trying to turn at the last second, you accidently wait too long and falling off the edge you would try to regain control all the way down, which is difficult as you fall down. A softer sprung car would be similar to running across a mound and go over the top while trying to turn you miss the top but you can still turn and return toward the top. You get the edge fast with a stiffer car but if you push it past the edge it is more difficult to handle.

What is the best combination? Like I said before it depends on your driving style. A web search on “oversteer vs understeer” will give you some ideas on how to adjust your suspension to match your needs and capabilities.

Rob