Chat to your local suspension gurus about what might be the right spring rate for your car and intended purpose.
Measure the installed height of your springs (to the nearest 5mm) whilst in the car at usual load.
Take out spring.
Take spring to local friendly springworks. Ask them to make spring to specified rate and desired installed height* and to the same dimensions as the spring you are holding in your hand.
Return later that afternoon, pay $80-90 per pair and install your custom springs.
*For struts, movement ratio is 1:1, so a reduction in installed height by x mm will result in the same reduction in ride height. Otherwise you'll need to multiply the desired reduction in ride height by your movement factor.
GT is right, except I've never seen a pair of custom wound/rated springs for that price !!! Anyway, follow his advice