It overpowers the induction noise, but not the exhaust if decatted.

Personally without the hi-pitched squeal the air thrashing sound is fantastic. One of my favourite traits of my car

Not all cars that are externally wastegated sound that terrible.
They have a tendancy to spit flames and sound like thunder which i can testify to since i fitted a screamer pipe that poked out behind the OSF front wheel to a supra and boy was that cool

You can run an external wastegate without a screamer pipe....

Yes you can, though it seems pointless since you may as well stick to an internal wastegate.

why do you think it's pointless? External wastegates are easier to use, and there is far less chance of boost creep if you are running high boost.

It sounds like a pregnant yak giving birth..