Is a turbocharger considered part of the engine assembly in terms of update/backdate allowances?
If it's not, then this thought just popped into my head:
2012 328 (4-cyl turbo) and 2012 335i are on the same line. That would mean you could take the bigger 335 turbo and put it on the 328. You'd have the lighter weight of a 4-cylinder, with all the power capability of the bigger turbo hotness. Discuss.