[ss3011]

There is a lot more to a torque converter than just stall speed . There is the torque multiplication, coupling point, and efficiency curve . Maximum torque multiplication happens when there is no output rpm, and decreases to 1 to one at the coupling point . Efficiency is zero at zero output rpm and approaches 100 % when output rpm approaches input rpm (engine rpm) . Since the converter works based on input torque, as you change things like the tire size, or the gear ratios ( both in the trans, or rear end ratio) this effects where on these curves your running . This is why you can see improvements in one part of the run , but lose in other points . As for modifying a particular converter , if you want a higher stall speed, a typical modification is to bend the pump fins towards the negative direction . This will raise the stall speed , but will also increase the multiplication, and the down side will reduce the efficiency . So you may see a better 60 foot time, but may lose mph . There are so many things that can be changed to dial in the "perfect" converter, but as we all know, change the weather, and you may need a different converter combination .