Originally Posted by apkano
Because of many engineering aspects, (aluminum grade, diameter, flow charistics, etc.) the NW intake does whistle at certain RPM's.
Mine does the same thing......actually I kind of like it. On more than one occasion I've had people ask if it was turbocharged.
Mine does when I just get into positive pressure (boost). I dont know if is caused by the NW CAI or if it just amplified the sound so you can hear it.