Help identifying engine noise in r53 please?

Hi guys. I have a 2006 R53 checkmate edition with 65,000 miles.

Tonight I heard the sound in this video: https://youtu.be/oJsEcJXTZ1k (sorry it's poor quality, hoping it doesn't matter) for the first time. I have just driven it quite hard for 10 minutes in fairly cold weather but I let the engine get warm first.

Oil changed 500 miles ago with shell 5w30 fully synthetic, I've checked its all topped up with no leaks.

Mods: 15% reduction pulley, milltek catback and davef style airbox mod.