Toyota Springs are set up with more spring in the rear of the axle, and less in the frount. I believe this is done to help cut down on spring wrap.
When I put in Mazda springs I also put a traction bar in to cut down on wrap. The more spring you put i frount of the axle, the more wrap you will get since the shackle will let the spring come forward.
This is just my idea, I have no scientific evidence to support my findings.