A body lift does not increse the distance between the top shock mount and the lower, You could put on a 12" body lift and run the same shock because nothing has changed in the suspension. 25 and 20" dont seem to bad though. Only thing to really do is install you lift and before putting the shocks on, stretch them out and see how much travel you will have. If you dont have what you want, then just run your current shocks until you can get the correct ones.. Running a shorter shock will only limit your susupension travel off road, so using them now will be fine but you will not win any suspension flexing contest, lol.