airbox lid

Guys - I was playing around on a back road and heard a bang so I looked in the engine bay and the airbox lid had came off.. thinking this was maybe loose I secured it fully and tried to pull it off and it wouldn't come off.. so I started off again and about 10 minutes later the same thing happened.. why is there so much back pressure? is anyone else having or have they had this problem? Could this be related to my engine noises I've had recently (see previous posts)

cheers!
 
REN-CEN on ebay quoted me £20 for it mate.

If your buying it off Karl you have to buy the whole airbox which is £70+ I think..
 
I've got an old air box where the pipe broke off the side. It can be glued back on, I just bought a new one. It comes with a filter and lid. Pm me if your interested.