Be careful with the K&N filters as you have to oil them. A mate of mine put one in his Hilux and the oil affected the air sensor and it had to be replaced.
I use an aFe washable air filter (
http://afepower.com/). No oil. I got it at AMAZON of all places for about $60.00 au and $12.00 au postage. I buy my oil and fuel filters there to.