Kay- Screamer pipe- Ie hes got an external wastegate and instead of it plumbed back into the exhaust it has its own unsilenced exhaust for the wastegate gasses to exit.

Nothing comes out until full boost as wastegate is shut, at full boost when the wastegate opens its incredibly noisy as no silencers or turbo to muffle the sound, loud as fook, it fookin SCREAMS, hence screamer pipe