I received the foam filter from Unifilter today and its a deal better than the OEM, in that it seals at the edges more positively. It could have done with a 3 mm oversize, instead of 2 to make it even better.
I followed the outline of the plastic support, which was a slight mistake at the bottom corners, where it should have followed the airbox instead.
I'll fix up the files at some stage. Send me a PM if you are in a hurry.
The UniFilter p/n is CF0581 & it cost AUD 27.23 plus shipping.
If I didn't already have a DNA filter I'd be more than happy to use this one, for 1/10 the price.