Get the timing wrong and you loose performance and create lots of smoke.
Most likely either:
- your car has a problem.
- your mates car, while being "a similar spec" has a different engine rating. Diesels of the same capacity, from the same manufacturer, are often produced at different ratings (e.g. 90, 105 & 120PS) for different models and markets.
Some fleets and lease companies deliberately specify the lower output engines to recude insurance costs.
Is your an ex-company car?
Superchips can get an additional 30hp out of the 2.1TD Xantia for �511.