1600-1900 rpm sounds like a friggin oboe. One really low resonant note that gets loudest at 1750 or so. I put the 6637 on an otherwise stock truck. Driver window down to hear it, but it's loud!

 

Intake drone, that is why some people switch to the AIS. with an open element intake there is nothing to muffle the noise.

 

Kwik switched from the 6637 to the AIS and noticed a big reduction in intake drone. The AIS isn't cheap, but if that drone really bothers you the AIS is about the only way to go in order to eliminate the sound and still have good airflow.

 

As long as its not the truck falling apart I don't care. Every now and then I like to turn the radio off and play name that noise. Btwn XM and cds I'll have no problem drowning it out. Thanks guys!