When it comes to low HP the 8 speed is better because there is a good gear for all speeds. But all that shifting is useless if you have to much HP. Real drag cars only have 3-5 gears so I feel that the 5 speed with the correct hp will be better than the 8 speed. How much HP is that number. I’ve replaced the torque converter with the 3200 stall fti so it should hold 650 TQ I believe.