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ELI5: What's causing the very high pitched engine noise and bangs usually Rally cars produce?

I come across videos of Rally cars, and played Dirt Rally, and in almost every documentation I see Rally cars have a different, high pitch and powerful sound, accompanied by loud bangs. What's happening? different engines or engine enhancments?
gpt
Straight cut gears (used because stronger than the quieter helical cut gears used in most road cars)will whine" at higher road speeds.
A blow off valve or BOV will vent excess turbo boost pressure when the throttle is closed, this generally produces a high pitched "squeak"
An anti lag system will delay the ignition after the throttle is closed so that the fuel/air mix is still burning when it enters the exhaust manifold so keeps the turbine spinning so full boost can be made sooner when the throttle is opened again. This makes the loud pops and bangs. Also massively shortens turbo life to around 1000km.