Alright, so ive got everything off and ready for the coilovers to be put on. It says i need to preload the springs, all i did was loosen the top 19mm nut. is that it?

now, my big problem is measuring the drop. I want to drop my car about 1.75", but where do i start to measure? do i make the entire coilover, from top to bottom, the same length as my stock spring/shock and then twist it so its 1.75" shorter? im confused. someone let me know. thanks in advance!