BUT, "I love it long time." I've got seconds behind IHCC.

IHCC has listed the correct checks. If you boost is still what it used to be (20 TO 22 W/O a tune), you don't have a cracked Y pipe.

Check the smell of the smoke. If it smells like oil, it is likely the turbo seal.......especially considering the low mileage. It probably dry rotted.

But, if you don't want to mess with it, I'm sure there will be some interest at that mileage.

 

Update: Still no smoke and still better boost than before with less throttle. Truck is running great but I have noticed one thing, between 1500 and 1800 rpm under light throttle I have noticed a low pitched whistle that I never noticed before. Could the new Y pipe cause that? I re-checked all the exhaust clamps and everything is good and tight.

 

Good news! If it requires hearing, I can't help much. However, I've read that some types of turbos whistle. Maybe it's the rebuild kit, turned it into a whistler. But, yeah, it could be a small air leak as well. Maybe a crack in a boot that's not visible.

 

Does the whistle change tone as the RPM changes? I hear my turbo way more at lower RPMs but the whistle is always changing as RPM/throttle changes - A fine working VGT is what that is...

 

Yeah it does change as the RPM changes and stops as soon as I let off the throttle. I only hear it between 1500 and 1800 and only when I give it light throttle. The boost looks good and the throttle response is great.