I just swapped in a lq9 with new rings and bearings and a trick turbo kit with 74mm precision turbo the first 3 days I had no smoke just a little at first tell I deleted factory pvc and just vented both valve covers then was fine, then today when I drive around it will randomly have grey smoke out exhaust then stop then come back any ideas it gets really bad when I am moving slow or backing up?

 

Note this truck just has a base mail tune on it also

 

Have you found the issue yet as I'm having the same problem but mostly on deceleration, same kit as yours with 74/75 precision, iv been told it's the drain going into the front of the pan.

 

Mine stopped after I found gasket maker in the return line

 

Turbo smoking is almost always due to a problem with the drain line. Either clogged, not steep enough (if its a gravity drain), or too small of a hose.

 

Other possibility is if it's a ball bearing turbo without a restrictor in the feed line. Ball bearing turbos often can't handle the same pressure that a journal bearing turbo can.

 

Or other possibility is the tune was and you clipped a piston