When I’m putting my SL 55 through her paces the transmission tends to not want to up shift after I have decided to not keep pushing. Eventually she will up shift and work normally. Is the system anticipating further spirited driving or is there something I’m missing. In normal driving the transmission shifts normally. This condition existed before and after “blue tops” and MK Ultra TCU additions.

I have same setup as you and recently had transmission issues. Mine was worse, transmission going into hydraulic safety mode (Neutral). I dropped the pan and it was full of shaving so now I am in the process of rebuilding or replacing it. I would suggest you drop the pan ASAP to check for shavings.

Thanks for the ideas Ideem.
When I installed the new "Blue Tops" I replaced the fluid & filter without evidence of ferrous metal shavings, thankfully. Unless I am using full throttle the system works perfectly, it only occurs at WOT. Maybe the system is anticipating continued WOT and wants to be prepared,

What you are describing has been normal behavior in the auto trans world for about 30 years now, or ever since the advent of electronic "learning" controls. It you drive like you stole it then suddenly turn into grandma, it will still hold gears for some amount of time before if figures out you have mellowed out.

Sure does make sense Triple Down!