The way to find the flash stall is cruise along at about 25-30 m.p.h in high gear and just stab it to the floor and watch the tach and see what it goes up to and that is the flash stall, sitting still and applying the brakes and bringing the r.p.m up till the car pushes is the foot stall, the flash stall is the important one. one thing to remember when getting a convertor is that the stall speed is'nt to high when driving around town,because if the convertor does'nt lock up, all it is doing is overheating fluid and cook'n parts. i use the B&M holeshot 2400 and it works great.