Depends on your RTA (or SA counterpart) regulations. I know that VIC Roads don't allow oiled filters, which means K&N are a no-go. Lukey make a high-flow replacement filter that is non-oiled and it's around the same money.
Don't expect much from a different filter though. Mine has a K&N and noticed exactly FA difference. The filter will allow slightly more air through but the intake is almost as much of a restriction. My fuel consumption MAYBE dropped a little - but I'm not willing to confirm that, as it might have just been slightly more air in my tyres or something equally ineffective. The only tangible benefit is that you don't have to go buy new paper filters.