What I have researched: Average life appears to be 300-500k miles. And, as mentioned, it's all about maintenance. Catch-up maintenance can be spendy. Look over my project link in my signature. This is a worst case scenario. Even if it is 'certified', I would have the timing belt replaced.
Atleast in the cummins world that is. With the cummins you can hold 1250 all day long. Anything over that and you are taking a withdraw from the engine and bank account. How big of a withdraw depends on how hot you go and for how long. With my engine on the rabbit I see 1200 to 1500. Depends on how much boost I run on the LP turbo.
Recommended gauges pptions of 15-PSI for stock boost cars, 30-PSI for tuned cars and 60-PSI for higher boost. Related Trouble Codes, MIL, CEL: P0299. 1.9-TDI Passat Shown. Similar on other models with 1.9-TDI engine. Locate the Maf and accordion hose near the right rear side of the engine:
tG7s.