do you think it would work out better if i did 4" in front and 5" rear?
Because you have a 4-runner and it's heavier in the rear, I think that would most likely work better for you. That's just my opinion though. I installed 5" & 5" and my front is a little more than 1" taller in the front. If I could go back in time i would install 4" front and 5" rear. I'm getting used to it now. I did switch from 5" shackles to 5.5" shackles on the rear and it helped a little. I left 5" shackles in the front. I'm also thinking about taking out the front shackles and re-drilling the holes to 4" and install them once more.
edit: I used to work for Greiner Buick Pontiac GMC in victorville, you related to them?