weeksy,

DNA or K&N stage 1 air filter - OE replacement
DNA stage 2 air filter box

PLus, if you are planning on keeping the bike then drill holes in the air filter box the ohter side to where the dna stage 2 filter is, and in my own personal opinion, fit a PC3 and get it dyno'd.

However, fitting the stage 1 and stage 2 alone will allow the bike to breath and you'll be surprised at the difference it will make

Cheers

WB