It's widely accepted the best intake for the MY03-05, is to maintain the factory airbox setup or to upgrade to the revised MY06 airbox with built in velocity stack. Whilst doing this, are there any benefits in choosing a particular type of panel filter to use? Each has their pros and cons, however the options are:
OE spec paper - ie Nissan, Bosch, Mann
Cotton gauze - ie Cosworth, K&N, GreenCotton
Multi layer foam - ie HKS, Pipercross, ITG
Although I don't do many miles per annum, I thought I'd swap out my lovely Cosworth filter for a Pipercross one as I've used these with previous cars and had no issues. My thinking is the multi layer foam filter should not only provide better filtration, but maintain performance for longer.
Velocity stack idea....
Cheeky
Swap out pictures showing each type of filter:
The following couple of links point towards aftermarket being a tad better than OE overall.