I'm baffled why there is still People out there that think McLaren or Honda dictated anything to another. Building that PU is a joint Effort and BOTH sides seem Happy with the way they are going. Honda is eager to show they can make a competitive PU as small as possible (read the bit "Lucky" posted above) and nobody at McLaren will complain if they can shrink their Bodywork.
Sometimes in these Threads one could mean they work against each other......