The RB20DET needs BOOST!
I went from the rb20det making 164rwkw on 15psi to the rb30det making 176rwkw on 9psi.
Engine size doesn't affect power, head and turbo airflow is what makes power.
Push 18psi in to it and it will crack your 200rwkw goal.
Speak to Chris32 what he thinks of his old Remapped ECU done by Martin Donnon compared to the PFC he now runs.
If I remember correctly he said the mid range power increased quite a bit with the pfc.
With regards to boost tailing off... This will aways occur with a manual boost controller to some extent, a cheapish option is to head down to your local turbo rebuilder and pick up a new wastegate actuator, down in Adelaide ATS sell an adjustable actuator for ~$120. You can select the preset also, from memory its something like 8psi, 12psi, 14psi, 17psi etc.
Where did u end up mounting the resistor pack?
The joys of trouble shooting a car that isn't quite performing the way you want it to.
Sorry I have to ask... Does it actually make any boost in first? Being an auto would have an advantage as it will spool a little earlier.