Having recently purchased a 330d e91 and then finding out about the swirl flaps failing I decided I would delete them as per the recommendations on here. On Wednesday I spoke to PMW who were extremely helpful.
Order was placed for Swirl flap blanks, round gaskets and square gaskets and for good measure I bought a vortex filter which I am really glad I did because when I got the cover off there was nothing inside where the filter should be!
My plan was to do the work tomorrow but as the weather was nice I started the strip down tonight, everything went so easy I finished the job tonight too, from start to finish it took two hours. Everything removed, flaps removed and blanks fitted, gaskets changed and manifold refitted, vortex filter changed and then everything bolted back on, I am well chuffed, I thought it would be difficult for some reason.
I can recommend this as a diy job because it really is straight forward. Only problem I had was that I dropped one bolt which was from the engine cover and is now lying on the plastic belly plate under the car, this will be retrieved tomorrow as I have the diesel tank breather pipe to replace and then the car is somewhere near where I want it.
The flaps I removed were in good condition and would have probably have lasted for a few years to come but I don't want that risk.