Just thought i'd post this up in case anyone else was suffering for the same issue.

Syptoms

At very light throttle i was getting a groaning noise it sounded kinda like blowing across the top of a pop bottle but very loud. I have a silicone TIP installed and a open cone filter so this probably made this more noticable on my car.

Cause

Air entering the tip and resonating across the top of the diverter valve. This maybe just my combination of TIP / Filter etc but after alot of searching i did find references to this being a common problem that Audi are aware of.

Cure

Well i just removed the diverter valve and blocked off the holes with alloy bungs, i know its not the done thing to run no DV but i prefer the noise. My DV was a 710n and my TIP is a toyosport one so this may be a contributing factor and i'll probably upgrade to Forge etc when i start running higher boost levels so i'll update this if the noise still exists with that fitted.