All the CAIs I tried made that horrible drone while towing our travel trailer. It was so loud you could not talk in the cab without yelling. That is what led me to develop the DWV intake mod. Check this out:
http://dygytalworld.ehost-services13...l#faq_snorkel1 You get a little power bump from it and it keeps the factory noise dampers which makes it tolerable while towing.