Not sure if im the only one thats done this. but here goes
I got hold of another standard Ph2 1*2 airbox bottom half and a new pipercross panel filter. I cut the bottom half of the airbox to bits leaving only the two mounting points to the car, all the screw holes for the top half and enough space to join a piece i made up with fibre glass.
Used the excess i cut from the bottom half as a template and made up a fibreglass piece that fits straight onto the bottom of the airbox. cut a hole in the bottom. bigger than standard, and then mounted a caf pipe into the hole.
The results were brilliant. and it looks standard when you lift the bonnet
il need to take pics to show you guys