Ok i have a 07 5.9 nothing special smarty jr set to cp3 five inch exhuast, cool air intake and a egt delete nothing to crazy. My problem is im starting to hear a noise like tist tist tist sorry best i can describe it, It doesnt happen at idle you can give it gas in park and nothing its when you get down the road for about five to ten min then it starts up not to loud but you can def hear in inside the cab if you let off the gas it goes away i thought it was a exhaust leak until i noticed only did it after warming up im suspecting a lifter anyone else have a comment? I run the right oil weight and the right amount i use mobile 1 are another name brand i always change both oil and fuel filter and always use fleet guard its been doing it now for about two months i no that sounds like a long time but im half deaf in one hear so i thought it was just a dodge engine noises i never noticed before but my friend road with me the other day and he said he could hear it good.

 

unload the Smarty and see if it goes away.

 

Could be this ...

https://www.dieseltruckresource.com/...r-t295034.html