I was just curious if anyone has used a K&N air filter and if so, are the gains any different from a SI engine? I'm thinking about getting one for the improved efficiency/fuel economy. Cheers.
I have one on my rabbit. I never noticed anything special. If you aren't smoking I'd say you don't need it.
More air flow in a filter usually means more particals getting into the engine

BTW I'll sell mine since the rabbit is out of commision