Dave Ett wrote:
I have also removed the web from the airbox lid, though I've no idea if this has any effect or not. I always intended to remove the one from beneath the filter, but somehow never got round to it...

Currently doing some reading about how to best handle the intake restriction...

I think it is not a good idea to remove the web in the the airbox which separates the "two" air boxes. There must be a reason Honda has spent the effort to design and manufacture this separarting wall. Some might argue it's just there to support the centre of the filter but I think there is a different reason.

Because of the 90° twin, the intake phases of the two cylinders overlap to a certain degree. The second piston is just moving at its highest speed (i.e. biggest vaccum) when the first is approching TDC i.e. if the airbox, filter and airbox intake holes restrict the free flow of air to piston 2, the flow caused by piston 1 will be "starved" by piston 2 sucking stronger.

I think the fact that Honda even gave the air box separate intake pipes strongly supports this theory.

Just some thoughts, maybe too theoretical...