The delay to Monaco could make sense, as I think they plan to also move some internals around and need Honda to do changes for this task. E.g. that huge cooler on top of the air inlet (marked red) could probably move much lower. They could split it up (yellow triangle). Similar to what they did in the last year with the Renault engine. This would also be in line with what Rob Marshall said recently about 'free gains'. They could then narrow down the cooling inlet. -> Lower cog and better airflow towards the rearwing.