You need to establish if it just smells of over rich blow by, or neat fuel. If you take the HPFP out and smell the oil around the seal and the recess it sits in on the chain cover, if it stinks of neat petrol, it's likely the pump, or a dribbling injector. Any rough idling or cold starting issues?
Remapped engines do cause the oil to turn black and stink pretty quickly. Tuners go way over the top with the fuel to cover their arses, and it means much more frequent oil changes as a result.
You can also rub a bit of the oil between your finger and thumb. Diluted oil loses a lot of lubricity and won't feel as 'slippery' as it should. That sounds weird I know, but it's an old school check I can't let go of
If in doubt with the pump, just replace the whole thing. It's about £180 from the dealer and you will get the latest revision. It's been updated a few times over the years.