Have you ever had one of those tubes (or heard one) thats a toy, and you swing it around real fast and the wind causes a high pitched humming noise? Well, my ex decides to sometimes, not always, but a lot of the time, hum like this at idle. It can be very loud and annoying. It started right after I put in my K&N FIPK, so i thought maybe that might have something to do with it, but I don't know what. Also my dad thinks it may be a fuel pump going bad, or the alternator straining to recharge the battery because of my system? Any help or ideas?