One thing to keep in mind when ordering a converter(buy a really good one for 9 second cars )is thtat the converter will have a differnt flash RPM in low gear versus high gear I have several different converters, 10 inch Contintental, nine inch TA and a eight inch TA. Another dilema is the motor output on the dyno versus what it likes to be shifted at in the car My 518 CI pump gas street motor made peak torque at 4500 RPM and peak power at 5600 RPM, Eddy RPM heads and a six pak intake and carbs. The stupid motor likes to be shifted at or above 7000 RPM with the ten inch converter and below 7000 RPM with the nine inch TA converter Like everything else in a race car you will have to test starting line stall and shift points to find the best RPM for each on your car