I love the music that my 72 ctd makes but the drone inside the cab is starting to get real old. At certain rpms I think my eyes are going to start watering it is almost like my head is stuck inside a tuba while some one plays a real low note. How do I kill this racket without destroying the beautiful sound coming out of my 4" straight pipe. I have read some posts about the aeroturbine, some say it kills the drone some say it dosent, seems like alot of money too.