To get more power out of it. Advancing the timing gives u a little bit extra. Its an old school way of tuning from the carb daya, now-a-days the timing is advanced on the ecu when it gets mapped. But from factory they only put a small amount of advancement in because its just a generic map For every car with that engine. Tbh the best way to get your 0-60 down.... Strip the living daylights out of it, it costs absolutely nothing