I have a stock 3" exhaust system without muffler and gutted cat, and have alot of resonance in the cab anywhere from 35-70 mph. I plan on getting the 4" exhaust in the future and was wondering just how loud it might be without the muffler. Right now whenever I'm going down the Highway, It gets pretty anoyying when your trying to listen too the radio( when it's hummin in your head ). But I still like to hear it at a low down growl when you get into it
, Thanks for any info 

