Its seems they made small redesign of the intake pipings.
Possibly small tweak in VLIM rearrangement. Step toward what they had in 2015/2016 units. In 2017 they reverted back onto h2o intercooler between V engine banks. so they need to redesign the header in intake pipings. Let me explain; in 2015/2016 they try to make narrower top assembly of PU (plenum, intake plenum, longer intercoling). I think the goal was reduce engine cover size presumably to aid aerodynamics.
In 2017 they add bulkiness in that area, because they return to the intercooler between engine banks. So they made wider dual Y ducting toward compressor intake. Sacrificing of higher CofG. But made main charge air ducting shorter and presumably more efficient. But harder to package. To make life easier they sacrifice the engine cover bulkiness and also swallow some mechanical penalty on already mentioned rised CofG.
If we look on pic below in 2017 they had more flat "circular" ducting. Maybe they change ducting angle of attack. Maybe beacuse:
1) to made some more space to sit intercooler little deeper into ice to lower CofG of total unit.
2)Or made just more efficient ducting just like they had in 2014-2016. I mean it is apparent that they prefered more "space" for piping&plenum above header before.
It is interesting all those decisions aimed for maximum PU performance. Even for sacrificing chasis performance. You increse CofG, bulkier cover. In this fuel limited formula, gained kJ of recovered energy really pays off.
a) It seems shorter ducting really made some savings of ERS boost kJ. Especially in hard transitional driver demands, lets say twisty partial to full throttle stop%go tracks. I think to much lag is wasted energy or even ducting resistance it is worth some saved kJ and even maybe some kW of peak power. But maybe not so big deal?
b) Maybe they gain more just from shorter packaging of total PU (reducing polar inertia). You don't have intercooler inside the tank and you could putt engine bay further ahead closer to ideal "cofG" centerline. Hmm all about compromise it seems.
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna