About to finally chop the airbox on my 2003 M800 and as I engineer a hole pattern I'm noticing this box inside the lid, right below the original air intake snorkel. There's a tunnel into this box from the snorkel. What's it do/for?
It is a resonator cavity. Presumably for noise abatement purposes. Air coming into the box makes the air mass inside the cavity vibrate.
it's airbox cancer :'(