I just compared the stock 98 GTP tables as well. For the most part, the table (max torque timing) is higher then the stock high octane spark. There are some cells where the timing is lower, but most of these will never be reached (.80 to .240 g/cyl and 2400 to 4400 RPM).The cells I did see that were lower and would be used were in the .68 to .92 g/cyl and 2800 to 4400 RPM.
Hmmm - wish we could get a definitive answer on this one. I am going to change my max torque timing table back to stock when I get my rocker arm (broke a Harland Sharp arm about a month ago, the replacement should be here Monday or Turesday). I'm interested to see what difference it will make.