A lot of people use the GA16 airbox from the Almera including myself.
I had a K&N which boiled on top of the TB, made the car sound like a chav wagon and it probably didn't help too much.
I don't drive the car hard at all so I rarely see the benefit of the airbox, but others say it does help.
I can't see an oil filter improving performance, just stick to a £3 one from local euro car aprts or something.
