My stock boost sensor (MAP) only reads up to 43.4 PSI of absolute pressue. All of my logs show MAP pressure flatline at 43.4 PSI and Actual Boost at ~28.6 depending on Baro. I should have monitored MAP voltage because it shouldn't flatline until 53.2 according to the sensor scaling at 5V. What that tells me is that the sensor only goes to 4V which is where 43.4 would fall on the sensor scale.
No matter how you scale it the sensor itself is going to be sending 4V (the max) at anything over ~29PSI of actual boost. Demanding above ~29 PSI of boost (~44 in the table) in your boost tables leaves the ECM trying to adjust the turbo to get more pressure than the 29 that it can see max, no matter what it does with the vanes the pressure always reads 29, even if your actual boost is at 40 on your mechanical gauge. At that point you have to start tuning using the vane position and max vane position tables. If you leave a big gap between vane and max vane you will have surges in boost from the ECM searching between the 2 trying to make your commanded boost.
Most places make a 5V 0-100 PSI pressure sensor (like the one I have for my drive pressure gauge) that you could drill and tap for then splice into the stock MAP's wiring. You would then rescale the sensor table (B0202) to go from 0-100 PSI linearly. The ECM would then be able to see what boost there really is and adjust the turbo accordingly and you should be able to go back to tuning for boost in the boost tables instead of the vane position tables. If I am still running a variable turbo when the motor goes back together I will most likely do this.
