I've finished to update the Mack E6 engine sound.
This sound has been long time ago recorded by my friend Tray Tudisca, and i've improved it with some new exhausts samples.
This sound mod is for the Harven's Mack R available here:
He will probably soon add the sound in his truck and update it.
But for the moment you can use that additionnal mod, be sure that it's in higher priority than the truck.