I just installed an aFe cai for my e90 330xi. I was wondering if a droning sound/vibration is normal between 3600-4000 rpm? The intake sound sgreat for higher rpms, but just around the 3600-4000 rpm range it sounds kinda like a "fart can" exhaust, and i'm not sure i like that. Any suggestions? I've tried putting weather stripping around the heat shield, not sure what other options are available to reduve this minor vibration/droning sound.....any suggestions would be much obliged...... thanks again in advance
I have a fart-can sort of noise as well at a limited part of the rpm range. I've got a K&N cone filter on there right now. I do believe it's what CR said, that it comes with the territory.
That's why there is so much design into the stock airbox with all those odd shaped chambers and foam inserts.
