The Pro Torque 12 " hi stall is the highest quality piece we have seen.We have opened many 12 " special GN converters and found them to not be furnace brazed,to not have updated clutch linings and to be poorly assembled and or balanced.The pro Torque converter utilizes a billet flanged drive hub,furnace brazed turbine and pump,quality lock up assembly,and many other techniques.This is a great piece.Most of these 12" converters will give 2400 to 2600 stall speed.