Fuel supply
A turbo build may need larger injectors, a stronger pump, upgraded lines, a fuel pressure regulator or a flex-fuel sensor depending on the goal. Running out of fuel under boost is one of the fastest ways to damage an engine.
Ignition timing
More boost often requires more careful ignition timing. Too much timing can create knock. Too little can create heat and lazy response. A good tune balances power, safety margin, fuel quality and temperature.
Sensors and logging
Wideband oxygen sensors, intake air temperature sensors, manifold pressure sensors, fuel pressure sensors and knock monitoring help the tuner see what is actually happening. Logging turns guesswork into evidence.
Do not tune around mechanical faults
Boost leaks, weak pumps, bad plugs, exhaust leaks, failing coils and poor grounds should be fixed before tuning. A tune cannot make a mechanically unhealthy setup reliable.