That sounds like something is loose or touching something it is not supposed to. Also, check your tip to be sure it is not under the bed of the truck. You want it just outside of the fender.Got my new MBRP exhaust (Single) installed and have a bad drone at around 1500-1800 rpm or when ever I give it a little juice. Any one else had this problem?? When I hook the 5ver on it is going to be to loud as it is now.