no filter will get you much more noise. Im assuming your intake is similar to the N52 which I have. You can get some more noise by getting rid of the intake muffler Theres a DIY for that somewhere. also you can do something like DJApex did. Lookup his eurobox mod thread for a DIY.
2007 Titanium Silver 328xi: FBO - headers. Upgraded suspension and brakes.
1985 Gazelle Beige 325e: Nursing it back to health from PO negligence.. Soon to be track car.