Okay, so a friend of mine has a small business manufacturing foam filters and induction kits, now for a long I've want to do something about the crappy airbox and it's multitude of bodged repairs it's seen. I've had my eye on a BMC CDA for a while but could never justify the expense for my measly 2 litre lump, so I spoke to him about putting something together based on one of the kits he sells, namely the http://ramair-filters.com/carb-race/frames-carb-race.html
Its a conical foam filter in an enclosed cylindrical airbox, with some ducting acting as a cold air feed.
Fitting was really simple using the supplied bits and pieces, the only slightly troublesome part was joining the MAF directly to the concertina section of the existing intake of the throttle body, as the MAF is slightly smaller by a few mm, luckily I had a rubber neck reducer in the correct size which I cut down to make a spacer. The airbox is supported by a bracket which screws into one of the holes left by removing the existing airbox. As for the intake feed I just routed that down and then back up behind the light unit where the existing intake was and cable tied it in-place.
So first impressions, personally I think it looks much better than before, there's definitely some noticeable induction noise (from inside the car) when driving it 'enthusiastically', and seems to rev a little more freely however I can't really comment on that as I'm sure much of that is down to the decat that was recently fitted, how it would affect a car with more standard exhaust setup I don't know.