Hey guys. Just wondering if anyone knows the specific differences besides the tune of the 2 x M274 engines in the W212 E250 and W213 E300?

M274 earlier years had some issues. Perhaps in the W213 later years they sort those issue out. This would be most important.
Tuning for more power is secondary. You sort out the mentioned issue first.

https://www.carcomplaints.com/news/2...problems.shtml

https://mbworld.org/forums/c-class-w...-you-bail.html