I had a K&N air filter fitted to the 2005 Mazd6 Luxury Hatch and noted very little if any increase in performance or response. I have just read a report suggesting that a fast flowing air filter like K&N is very risky for the EVO IX as it risks the engine due to increasing the lean burn of the engine. An engineer for Mitsubishi said that the standard set up was better. Has anyone fitted a K&N air filter to a MPS? If so are there any discernible benefits other than psychological? Thanks.