Do you have an auto or 4 speed? Just to let you know, my car was running 12.3 with the stock converter and when I switched to a good one, the car ran 11.5's. Almost a full second with a $450 converter.
There's the proof that a good converter will really help and that it is often overlooked or scoffed at due to the price tag and a cheaper converter comes in its place. A cheap converter has its place. Ether on a ride your not concerned about with the time slip or the garbage.