OK, here are the figures. 1957 T'bird, 341 y block making just over 400, weight is 3400 with driver, 456 mini spool, 28" tall slick, running a C4 and an 8" convertor. The 15 year old convertor was swapped out for a new one and the big "promised" .25 sec and 3 mph did not appear. The car runs right at 12.90 and 102 mph. The 60 foot is the same, launch feels OK, it was in similar track conditions to what we have run in the past. Guess my question is...did we have our hopes too high...was the sales guy a smooth talker...has nothing changed in convertors in 15 years???