Start with what the car actually did. Then test one change at a time.
The rebuilt What-If uses a real log as evidence, keeps hardware limits separate from tune requests, and shows Boost, Fueling, Timing and Power on separate readable graphs. It refuses calculations when required data is missing instead of filling the gap with a fake number.
Load a baseline log first.
The simulator will explain the baseline, the proposed change, the likely hardware limit and which parts of the result are actually supported by logged data.
Choose a log to unlock the graphs.
Boost, fueling, timing and power are separated so unrelated units never flatten each other.
Can the current parts support the request?
These checks are deliberately conservative. A catalog turbo rating is a capability reference, not a promise that the engine will make that horsepower.
Problems already present before the test tune.
The What-If should never give extra power credit for a condition the real log already shows is being corrected or limited.