OK here is what I was told:

...that when you upshift the TC engages and the brief lag comes from the time it takes for it to "spool" and build torque so that you will have more power and a more direct shift into the next gear... can anyone confirm

2003.5 5AT
Premium Package
Tire/Wheel Package
K&N Filter, Z-Tube, EGK

 

I think it lags because you're not telling it to shift now.. it's more of a "you can use this gear when you get around to it" kind of thing. You have an '03.5, like me. The "manual" mode is a top-gear selection, not a current-gear selector. The tranny will still pick and choose between 1 and whatever number is on the dashboard and jump between them like an automatic.

 

The AT requires torque control [the AT [TCU] signals ECU to decrease ignition advance] just before, then during the shift, after the shift the advance ramps back up slowly.
All designed to lengthen life of AT and make a smoother shift.

 

That sounds on target for the sedan, but this was the explaination for the my coupe though which is current gear selection.

2003.5 5AT
Premium Package
Tire/Wheel Package
K&N Filter, Z-Tube, EGK

 

And that issue is addressed by the TS ECU, not the power stays in all the way up during shifts.

Gurgen