question about slotted sub frame spacers

OK, I just got my set of subframe spacers and I remember reading somewhere that you can put in just the top half or bottom half for a mix of comfort and performance. but which is it? if your only putting in half, are you supposed to put in the top half or the bottom half? then I’ll see if that is enough or if it needs the other half.
thanks

If you already have stiff coilovers, how much harsher and unbearable will the ride be in comparison? I’m considering them if the benefits are worth the harshness.

It is the second best mod i have done to my car. The slotted ones are barley any harsher, but the reduction in wheel hop is great. The only noise you get is if you have a stripped back half of the car and you don’t shift into second (aka rev’s too high or to low)