If you have the Limited, you have an air bag, that bag runs off a compressor, unfortunately they don't have a Schraeder valve set up under the seat, and the computer has a set ride height that it will try to maintain; and believe it or not, that bag works like an overload on a truck. If you unhook the 1/4" line at the end of the line that goes from the bag to the pressure collector and put a Schraeder valve in it, you can manually fill the bag to your desired stiffness. But beware, that bag is only rated for 90 psi! So use a bike pump, or something that you can control, because it doesn't take much to gain or lose air! And you'll have to disconnect the compressor, and the collector so that it doesn't run away and fry itself. If you have the standard F3, then the only thing you can do is get a beefer spring for your shock; or get an aftermarket shock set up for the weight you're carrying.