Hallo daar Ben,
You can use a K&N filter. It is of very high quality and lets in no dust as far as I can see. I used only the replacement panel filter which goes into the standard airbox. It gave a nicer, deeper sound. It sounds a bit like it has sidedraught carbs! I also rerouted my air inlet tube (with brake duct cooling hose) to the grill below the bumper to get some cool air fed into the air intake. It gave a slight increase in power/torque, but i have no figures.