Cool will give that a try, will be great if its just the software! Nope original PCV.  I've checked its ok by removing the oil filler cap.  It ran rough when I did this so I'm assuming that means the PCV is ok??
Just had a look at the link.  sounds sort of similar except the noise I'm getting isn't a flutter.  More like the wastgate is open briefly rather than open/shut/open/shut.
A mate told me today it sounds like I'm getting a boost spike.  Which would mean that everything was working as it should be as the system is protecting itself from overboosting by opening the wastegate.  So...what would cause a boost spike? The software? It's been perfect the last 10k i've had it on for, why start spiking now?
Initialy I thought my problem was either the N75 (not checked yet) or the charge air pressure sensor G31 (not checked yet) but now that my mate said this I have no idea! 

Any thoughts anybody???