that box is the resonator.  it helps tune the intake so there are no
flat spots in the intake charge curve.

bottom line rafi, you're not going to get a lot of enthusiasm on this
group for the mod you're proposing.  there are a number of potential
problems including decreased engine life with decreased filter
efficiency, and the risk of water ingestion - not good.

if you want bolt-on performance, go for a better header and a more
aggressive cam.  after that, look into getting the head ported and going
for higher compression pistons.  before any of that though, make sure
all your ignition components are in top condition.  iridium plugs and
magnecor plug leads for example won't magically give you more power, but
they will definitely make sure you don't lose any along the way.  also
make sure the valve lash is set right, that the timing belt is set and
tensioned correctly, and that the ignition timing is correct.  also,
make sure you have that "max power" thing down.  not sure what your vtec
crossover rpm's are on your motor, but the max power for your motor is
way up there near the red line - hondas have no torque, so they won't
"grunt" you off the green light, but with the motor spinning fast
enough, they perform quite decently.