Need advice for slowing my car down consistently.

DO you have a way to pull out timing with RPM? I effectively slowed a car from 11.13 down to 12.0s short shifting and having 10 degrees of timing pulled out past 4500 RPM. Dropped shifts from 6300 to 5600. I was using a lockup converter, so the early shift into 3rd with lockup really slowed it down. Look into a high speed timing retard.