I think SSpdDmon is teasing us.
My car had a dip in TQ/HP right around 4k (a lot of LSX's do). Since I had a copy of his tune from several years back..I think that was his way of teasing us about 'copying' his tune.
In all honesty, I did utilize his Idle and Learning Airflows almost verbatim. Since then I have done my own Desired Airflow, Spark, and TC. I still use most of his TF settings.
That 4K dip is fairly normal...