[R.G.]

N54 can easily be tuned. That engine has a bunch of exciting stuff out and in development. I can't speak on any electronic / accessory issues but I own two N54's and as long as they are maintenanced well, the engine is rock solid. Neither of mine are under warranty but I have also become handy with a wrench since ownership.

Some issues that are deemed the more common issues (at least they are on my E92 N54)
1. Injectors (those have 100k or so warranty on them due to recall)
2. Water pump. Typically a good idea to replace around 50-75k
3. Cold start rough idle. Honestly if you tune, it turn cold start off via tuner. This never was an issue with my tuned E92 but the F02 still has cold start active and it is not as smooth as it should. Don't let car sit and idle on cold start if active. Turn on and go.
4. Turbo seals / smoking / wastegate rattle. Mainly from running stock turbos too aggressively. If not driving the car hard then it should not come up.

Lastly is carbon build up on intake valves. Nature of direct injection. Walnut blast cleaning of the valves can be done every 75k or so and it will restore performance. The more you cruise and not drive aggressively the more carbon build up you're likely to have.


Hope that helps a bit.