If the shocks are a limiting factor then you simply find shocks that are longer that will meet your needs. Remove them and flex it on both sides and measure the needed fully extended and fully compressed length. Check to see if your Pro comp arms come in contact with the axle mount on full droop. Stock arms will contact and limit down travel and simply cutting that bracket to avoid contact will give you a little bit more droop. I may be wrong here, but it seems like the track bar and steering components can limit down travel as well. Also, if you havent put disconnects on your front axle and removed the sway bar from your rear axle, that will give you a ton more flex alone. Just make sure that youre bumpstopped enough that the wheels dont get wedged against something like your bumper, body panels or inner wheel wells. Once they get jammed against something its like putting the brake on on that wheel. Since that wheels is stuffed, thats the one with the traction as well so the drooped wheel will have to fight that much harder to overcome the stuffed wheel ( when its contacting something of course) With what looks to be a fairly mellow control arm angle, you should be able to get some pretty good flex out of your rig. I was at 3" and had to relocate the brake line mounting location because the stock lines were getting stretched pretty bad. You shouldnt have any issues gettting at least that much out of yours as well.