Automatic transmission announces the friendship

It was clear to me that the automatic transmission in the 9-5 is not too good to talk about proper torque, but if you get it yourself, you can hardly believe it. The symptoms are not even so bad with me, but I think that’s still coming. A friend carries a 9-5 Aero and I have something that was a 2.0t, but now has about twice the power. The Aero is similar, and both cars bring at least 440 Nm. For a few weeks we both observe that When switching from “N” to “D” or “R”, the gearbox takes about a second of time before it can be felt (not hoerbar) and grabs with a jerk. The Aero has it now actually constantly, my car increasingly frequent. While driving, the gearboxes then switch quite normally, i.e. not somehow rough. Naturally, we all know that the gearboxes are not designed for this power and that it has to come earlier or later so. So we do not need to discuss this here. There is also no complaint about the repair, which is probably not quite cheap. What interests me is the question whether it is done with the replacement of the valve housing (Art. No. 5449780), as we were told here, or whether the symptoms suggest that more needs to be exchanged. What is the possibility of the complete gearbox? Or is there even a more favorable solution? I assume that a repair and even a complete gearbox replacement will not last a long time. If we continue to add such torques to the gearbox, what is it like to convert a 9-5 from automatic to manual transmission? With the old 900s and also with the 9000 it was possible to do so, but how does it depend electronically in the 9-5?