yup I have done exactly the same as rashcupra, I have removed the restrictive flap.
only I think the bit he has blanked off is a water escape route
there is a little hole at the bottom of the airbox so if water does get in there it will just drip out of that! that little slot at the bottom lets out half the cold air thats just about got in there so sealed off will make a huge diffrence
here are some pics to try and show what i have done il mod the airbox lid at work tomorrow
that might make it even better
EDIT: FRONT PANNEL is on the wrong side the pics are you looking from where the air is going into and the air escaping arows are the wrong way round but sure you get the rough idea
when im moding the airbox lid maybe there is some water in the airbox maybe that could be all the condensation smoke out the back