Thanks for the heads up on that Mitch!
I'm going to try and get this done tomorrow so fingers crossed the screws haven't seized in their inserts (although given the state of the screw heads I'm pretty pessimistic about that). I had a look at your post, your mate did a fantastic job, if only I had access to a lathe and some dies! I'm going to remove the entire assembly from the car to work on it rather than in situ I think. It most definately is the most bonkers air filter setup I think I've ever seen lol