Alot of modulators are adjustable, it will have a flat head screw inside the vacuum line side of the modulator, one or two full turns of the modulator screw will make a huge difference, turn it out for a faster shift in for a longer shift.
It may be hard to get to the screw you need a small driver and the cross member gets in the way, if you pull the modulator out to adjust it, you will start dumping trans fluid like crazy on your floor.
The modulator does control the shift I adjusted mine in because the shift was too fast when I stomped on it. 2 turns in on the screw made the shift perfect.