converter slippage

Is 16% slippage excessive. Purchased a new 8 in. custom converter from a reputable company not a cheapie. This is in the 1/8 mile. Will it lock up more in the 1/4 since it should be past its max hp rpm. Still pulling hard on the converter in the 1/8. I'm at 6200 in the 1/8 at 103 mph. Going to run the 1/4 this weekend and don't want to run out of rpm. 7200 is the max I want to turn. Car has 4.56 gears and 29.5 slicks. How much rpm approx. will I gain in the last 1/8 mile. I know there a lot of other factors. Just want to know from your experiences. Thank you.