for you guys running twin turbo i just finished a new run of our 2.28 /1.48 planetary gears for the th400 .what this does is permit traction when too much torque is applied to the tires .alows 30 more mph in low gear and reduces sprag failures by reducing hi drum speed on a gear change .we also make a 2.66 /i.66,a2.75 /1.57 ,a 2.84 and a 2.40/1.40 for cars who need more torque multiplication off the line .call ckperformance .com for the proper ratio for your application.later.