My favorite mod to a 6 screw floating bridge guitar is to loosen the strings, remove the springs and tighten the 6 screws so not only does bridge not move, it is tightly attached to the body. I also put back the springs. This increases sustain, cuts treble and boots the middle and bass. I've done this on my 1962 Strat and a Yamaha with the same noticeable effect on both. I'm no scientist but as I see it the strings are then affected more by the mass of the body. Either that or a lot of string energy is lost using a floating bridge.