[marklubi]

The popping sounds from a turbo car is from the wastegate (whistling sound for a blow off value) when the system is releasing pressure from the turbo that was built up. It prevents over compression that would damage the engine.

[whackernews]

I’m not talking about a dump valve, I’m talking about an ALS as I’ve mentioned. This is where the engine timing is delayed which results in some combustion to happen in the exhaust (hence literal pops). This is used to keep the turbo spooled by MAINTAINING pressure across the system. It’s a performance system.

If your dump valve is popping I think there’s something wrong!

https://en.wikipedia.org/wiki/Antilag_system