Quick answer, going to a higher stall convertor does two things. One, it allows your engine to rev higher. That helps if your torque peak is above what your torque convertor allows the engine to "stall" at right now - which is very likely the case for you. Two, it increases the torque multiplication slightly.
Both these added together can help a little or help a lot depending on how "hot" your cam is. Usually going from a stock convertor (stalls at about 2200 rpm) to one that stalls at 2800-3000 rpm will drop about .4-.5 seconds from your 1/4 mile time. It'll also cut about 1 mpg from your fuel economy. Next question: do you have enough traction?
