The trans throttle pressure rod effects trans throttle pressure which effects the shift points along with gov pressure and the shift valve spring. What happens is the trans has gov press and trans throttle press working against each other basically. Gov press goes up as the driveshaft speed increases and as gov press goes up it will move the shift valve over when its high enough. But the shift valve has throttle press and a spring on the other side and the gov press has to work against trans throttle press and the spring to shift the trans. So as the car speeds up gov press goes up and when it goes fast enough for the gov press to overcome the trans throttle press and the shift valve spring the gov press moves the shifht valve over and the trans shifts. But as you know when you go faster the shift points go up. Thats because when you step on the gas more you move the trans throttle press rod and when you move the rod it raises throttle press in the trans so you have to go faster now for gov press to overcome the throttle press and spring and now the trans will shift at a higher speed. If the throttle press stayed the same it might shift into second gear at 10 mph on light throttle or at full throttle. So basically throttle press works with the gas pedal linkage so when you step on the gas the throttle press goes up to raise the shift points. Now if you lenthen the trans throttle press rod you will raise the throttle press at that point and the shift point should go up. But remember it takes throttle pressure and gov press along with the shift valve spring to determine the shift point. Basically gov press on one side of the shift valve works against throttle press on the other side of the shift valve. So anytime you change the throttle press , gov pres or the shift valve spring tension it will effect the shift pont. Hope that helps some as its just a quick reference to give you an idea of throttle press and how it works. Ron