from what I've read, re-arching is kind of a temporary thing, meaning they will just go back to where they were before. :( and it won't increase the rate so they will still sag under a load. I vote for a combo pack. use the 2wd pack's main (or whichever main is in better shape), cut the eyes off the other mains as leaf #2, then the next 4wd leaf, then its matching 2wd, then 4wd, then its matching 2wd, etc. assuming everything is in decent shape, that should give a small height boost and plenty more load power.