What are the pros and cons of ECU flashing?

[SanJudah]

The advantage of ECU flashing is that it modifies important parameters such as fuel injection volume, ignition timing, and intake air volume of the electronically controlled fuel injection engine. It can be understood as a recalibration to release the reserved power and fully exploit the car's potential. The disadvantages of ECU flashing include higher requirements for fuel quality—originally requiring only 92-octane gasoline, but after ECU flashing, 95-octane gasoline is needed, and fuel consumption may become abnormally high. It can also disrupt the overall balance of the vehicle, lack suitable parts in the supply of accessories, and impose higher temperature requirements on the engine. If only a Stage 1 flash is performed, which involves modifying only the ECU data without changing the original state of hardware like the exhaust system or catalytic converter, it will not cause issues during annual inspections. If a Stage 2 flash is performed, it can also pass the annual inspection by replacing the catalytic converter with a high-flow one.