it's been awhile since i looked at one, hopefully i remember it correctly...
the gov is driven off the tailshaft, as RPM's increase the gov arms try to swing outward (the more weight, the earlier and farther they move), this movement is also limited/slowed down by the springs. as the arms move outward they push on a (pair of?) check ball. as the ball moves in, it allows ATF to flow around it instead of through the main system. this fluid dumps to the pan and drops the line pressure.
so the stiffer the springs or the lighter the weights, the less bypass and the higher the line pressure. higher line pressure=later and harder shifts.
i have heard of people replacing the springs with solid rods or welding the check ball hole shut, but this may be for racing only. i don't know if it's ok for the street. but i don't see why not, it will give you extremely hard shifts which may not be comfortable, but they don't necessarily damage the trans (IIRC they actually preserve the clutches and bands). and the line pressure will still be controlled by the TV assembly.