S54? Seriously? Iron block? Great for an I6 but even a S38 is up there and better if we take time into context. S54 really peaked the I6 iron block development, however it's a dinosaur by newer standards.
I have no interest in messing with my N54 other than simple bolt-ons, small improvements, and maintenance. Should it let go or even the turbos for that matter, S85 will seriously be considered.