Oh the tech gods are going to flame me on this.. but let me share my experience. I've been here before; its not an issue and more visible in 6MT cars because you control clutch engagement. It's the flywheel rattle ; you wont here it if the clutch is disengaged and you only hear it when the clutch is engaged and your are in neutral gear. Sounds annoying I know, but it only gets louder if you change it to LWFW or a lightened dual mass flywheel. Same PTA was in the 335i in 6MT cars; I am okay with this.
Like any other noises you hear in the M3; Cold Start Growl; Raspy Exhaust; Squealing brakes at low speed - just tell your peeps its the sound of performance and you paid for it.
E90 2008 BMW M3 - 6SPD - AW
E90 2007 BMW 335i - 6SPD - SG - Sold