N53 engine differences?

Folks

In the F10 (and E9x's, etc.) the N53 engine was used in the 523i, 528i and 530i with power outputs of 204bhp, 258bhp and 272bhp, all in 3.0 capacity.

Does anyone know what the differences there were to account for the different output's? Was it confined to mapping/ECU differences or were there physicall differences in the engines themselves (e.g manifolds, etc), does anyone know?

Thanks in advance!