63 plymouth was going 10.21 with just indy 440-25 crossram in same air. i added the indy epoxy inserts and off the trailer 1st a 10.13, then i short shifted to 6000-6100 and it goes 10.04. put in the new converter and goes 9.978. car is 3856 lbs. air was 500+ DA,same as the last few times out.so in my application they do work.