I'm gonna guess that most of you guys have never heard a 6. 0 with the same intake/exhaust mods that you are refering to. The 6. 0 will whistle to the point of not being able to hear the exhaust tone at low RPM's. I have made all the mods to make my 5. 9 as loud as it will get, but it pales in comparison to the 6. 0.
In my opinion, the 6. 0 whistle is just plain obnoxious. I heard one at horse camp a couple months ago. I could barely see the truck through the trees, I could not hear the engine or the exhaust, but the turbo whistle could be heard throught the whole holler.
I like turbo whistle, but I like exhaust notes too!