Deciding to stick with the monster Ramair filter, I bought a couple of bits to help make it fit. They were a silicone elbow, an alloy joiner, a couple of clips and a bracket to support it from something...

The idea was to get the air filter under the higher part of the bonnet and angle it down slightly to aid clearance. I think it came out alright!

http://distilleryimage1.ak.instagram.com/de826956a20211e397a10eb94f794f39_8.jpg

I am tempted to do a little bulkhead shuffling at some point (maybe when I cut some carbon to shape for a carbon bulkhead!) and build an airbox to use the redundant bonnet louvres usually used for the heater. The louvres might have to be reversed for the best effect, but this wouldn't be too difficult I'm sure (for someone who knows what they're doing, anyway).