you can simply spin down the spring perches, but as stated when you raise the car up off the ground you are going to have no preload and your spring may unseat itself and not go back properly when you lower the car back down. If you really want to get into it, i had a look into the tube itself, and there is quite a bit of more space that the shock can screw in, but theres a ridge on the inner wall that stops it from screwing in any more, technically you could get this machined out and it would screw in a little further.