I experiemented with a few setups on my 3.0 X5...did an aluminum bend to the airflow meter with another aluminum bend to a large cone filter. Wasn't happy with the high pitch whistling to be honest haha. Would make my face cringe up during light acceleration.

I ended up going with a new bmw air filter and added a 2.5" velocity stack out the front of the OE air box facing the back of the headlight. Noticed about 0.4K/100L of improved fuel economy with this...and only has audible induction whistle from outside the vehicle :-)

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- 2001 X5 3.0i Titanium Silver -