People seem to be getting concerned about the L series overheating, however to my knowledge no-one who hasn’t got a suspect headgasket has had cooling problems. My answer to this is simple. If it doesn’t overheat then don’t worry about it! If you experience overheating when driving hard then ease off and the temperature should fall. If it doesn’t then something is seriously wrong, most likely a faulty thermostat, low coolant level or faulty fan (or sensor for it).
The L series block is virtually the same as the T series one and even shares the same water pump. The T series petrol turbo engine is 200bhp as standard and 300 bhp is readily achievable without cooling issues. Petrols also run hotter than diesels as they have a lower thermal efficiency so it is unlikely that the L series will have any cooling issues for a long time yet.