Cat C9 High Soot Levels

Iam trying to find the cause of high soot levels in our 2013 built D6R, S6T00779.
This is a tier 2 motor.. we had some discussion about it here...https://www.heavyequipmentforums.com/threads/d6r-track-wear.76755/page-2
The dozer had new injectors and heui pump about 200hrs before we bought it.
It had 5400 hrs on it at that stage, but before working it we had our Cat dealer give it a 6000 hr service...so changed every drop of oil, coolant, filters etc. as well as checking valve...

Cat C9 High Soot Levels