I spend close to $300 only since I wanted to ensure correct fitment rather than making an intake myself for a fraction of the cost. however, when I took out the old air-intake box assembly, I realized the poor fitment. I had to professionally get the heat-metal shield cut to proper size, in addition, the hose adaptor for where the intake sensor goes was so poorly designed that it, in fact damaged the sensor! the adaptor was incorrectly shaped and did not fit. WORST PURCHASE!!
Improved air flow but...
Installed CAI and within 5 miles of driving the CEL came on. Took car to BMW dealer for service. Trouble code indicated lean air/fuel mix. Removed the CAI and reset computer. CEL went away and has not returned after 75+ miles of driving. Good looking product and improved air flow but I don't want to potentially burn the valves on a car with only 6k miles. Will not use CAI and will return for refund.